Microbiology & Immunology
 Multiple Choice Questions Database

 

Key Code: I

An ELISA designed to test for the presence of serum antibody for a new strain of pathogenic bacteria is under development. Initially, a monoclonal antibody specific for a single epitope of the organism was used both to sensitize the wells of the ELISA plate and as the enzyme-labeled detecting antibody in a conventional sandwich ELISA. The ELISA failed to detect the antigen despite the use of a wide range of antibody concentrations. What is the most probable cause of this problem?

A) the antigen is too large
B) the antibody has a low affinity for the antigen
C) the monoclonal antibody used to sensitize the wells is blocking access of the epitope, thus when the same antibody is enzyme-labeled, it cannot bind to the antigen
D) the enzyme-labeled antibody used should have been a different isotype than the sensitizing antibody
E) the monoclonal antibody used is probably unstable

Answer: C

(Year Posted: UI 1)

 

Key Code: I

An 8-month-old baby has a history of repeated gram-positive bacterial infections. The most probable cause for this condition is that:

A) the mother did not confer sufficient immunity on the baby in utero
B) the baby suffers from erythroblastosis fetalis (hemolytic disease of the newborn)
C) the baby has a defect in the alternative complement pathway
D) the baby is allergic to the mother's milk
E) none of the above

Answer: E

(Year Posted: UI 2)

 

Key Code: I

A 50-year-old worker at an atomic plant who previously had a sample of his own bone marrow cryopreserved was accidentally exposed to a minimal lethal dose of radiation. He was subsequently transplanted with his own bone marrow. This individual can expect:

A) to have recurrent bacterial infections
B) to have serious fungal infections due to deficiency in cell-mediated immunity
C) to make antibody responses to thymus-independent antigens only
D) all of the above
E) none of the above

Answer: E

(Year Posted:  UI 3)

 

Key Code: I

Which of the following immune deficiency disorders is associated exclusively with an abnormality of the humoral immune response?

A) X-linked agammaglobulinemia (Bruton's agammaglobulinemia)
B) DiGeorge syndrome
C) Wiskott-Aldrich syndrome
D) chronic mucocutaneous candidiasis
E) ataxia telangiectasia

Answer: A

(Year Posted:  UI 4)

 

Key Code: I

A healthy woman gave birth to a baby. The newborn infant was found to be HIV seropositive. This finding is most likely the result of:

A) the virus being transferred across the placenta to the baby
B) the baby is making anti-HIV antibodies
C) the baby's erythrocyte antigens cross-reacting with the virus
D) the mother's erythrocyte antigens cross-reacting with the virus
E) maternal HIV-specific IgG being transferred across the placenta to the baby

Answer: E

(Year Posted:  UI 5)

 

Key Code: I

A 9-month-old baby was vaccinated against smallpox with attenuated smallpox virus. He developed a progressive necrotic lesion of the skin, muscles, and subcutaneous tissue at the site of inoculation. The vaccination reaction probably resulted from:

A) B lymphocyte deficiency
B) reaction to the adjuvant
C) complement deficiency
D) T cell deficiency
E) B and T lymphocyte deficiency

Answer: D
(Year Posted:  UI 6)

 

Key Code: I

The most common serologic test used for the detection of HLA antigens on lymphocytes is:

A) the complement fixation test
B) double gel diffusion
C) complement-dependent cytotoxicity test
D) mixed lymphocyte reaction
E) radioimmunoassay

Answer: C

(Year Posted:  UI 7)

 

Key Code: I

Serologic testing before kidney transplantation reveals that the leukocytes of a prospective recipient are killed by the following anti-HLA antibodies in the presence of complement: anti-B27, anti-A1, and anti-A3. You can conclude:

A) that the prospective recipient expresses the B27, A1, and A3 HLA specificities
B) that the prospective recipient does not express the B27, A1, and A3 HLA specificities
C) that the potential donor and the prospective recipient are not siblings
D) that the potential donor and the prospective recipient are not identical twins
E) that the prospective recipient should not receive a kidney graft that expresses these HLA specificities

Answer: A

(Year Posted:  UI 8)

 

Key Code: B

The formation of colonic ulcers and abscesses during Shigella dysentery is due to ...

A) the ability of bacteria to survive stomach acidity because of the production of urease
B) bacterial survival within macrophages
C) invasion of enterocytes and cell-to-cell spread of the bacteria
D) bacteremic spread of the organisms
E) production of heat labile (LT) enterotoxin

Answer: C

(Year Posted:  UI 9)

 

Key Code: B

An 8-year-old boy living in a wooded area of Virginia suddenly develops fever, headache, and myalgia. On physical exam, a rash is noted on his wrists and ankles. Within hours, the rash spreads to his trunk. No organisms are isolated from 3 sequential blood cultures. The child is treated with tetracycline and recovers. Serological studies on acute and convalescent serum samples from the child are MOST LIKELY to reveal that the etiologic agent was ...

A) Borrelia recurrentis
B) Coxiella burnetti
C) Franciscella tularensis
D) Rickettsia rickettsii
E) Yersinia pestis

Answer: D 

(Year Posted: UI 10)

 

Key Code: B, Key Code: I

Which one of the following licensed vaccines is MOST LIKELY to elicit a T cell-dependent antibody response in a 13-month-old child?

A) Hemophilus influenzae type b conjugate vaccine 
B) Meningococcal polysaccharide vaccine group A
C) Meningococcal polysaccharide vaccine groups A, C, Y, and W-135 combined 
D) Pneumococcal polyvalent vaccine

Answer: A

(Year Posted:  UI 11)

 

Key Code: B, Key Code: I

For questions ___ to ___ match the MOST EFFECTIVE host protective immune mechanism with each organism below. An answer may be used more than once.

A) Agglutination of the organisms by anti-pilin antibodies 
B) Contact-mediated lysis of the organisms by cytotoxic T cells 
C) Intracellular killing of the organisms by activated macrophages 
D) Neutralization of toxin by antibodies 
E) Opsonization of the organisms by anti-capsular antibodies and then phagocytosis by polymorphonuclear leukocytes


____Streptococcus pneumoniae

____ Clostridium tetani

____ Clostridium botulinum

____ Brucella abortus

____ Neisseria meningitidis

____ Legionella pneumophila

____ Corynebacterium diphtheriae

Answer: 

__E__Streptococcus pneumoniae

__D__ Clostridium tetani

__D__ Clostridium botulinum

__C__ Brucella abortus

__E__ Neisseria meningitidis

__C__ Legionella pneumophila

__D__ Corynebacterium diphtheriae

(Year Posted:  UI 12)

 

Key Code: B

A 22-year-old develops an abscess in his peritoneum following rupture of his appendix. Gram stain of the exudate from his foul-smelling abscess reveals numerous polymorphonuclear leukocytes, Gram-positive cocci, Gram-positive rods, and Gram-negative rods. Aerobic culture of the exudate at 37oC on blood and MacConkey agar plates yields only enterococci. Which of the following bacteria is MOST LIKELY to be among the Gram-negative rods?

A) Escherichia coli
B) Proteus mirabilisi
C) Legionella pneumophila
D) Moraxella catarrhalis
E) Bacteroides fragilis
F) Peptostreptococcus micros
G) Prevotella melaninogenica

Answer: E

(Year Posted:  UI 13)

 

Key Code: B

A 20-year-old women presents at a local clinic with fever and abdominal tenderness. She is at day 2 of her menstrual cycle and reports having had unprotected sexual intercourse a few weeks earlier. Gram-negative diplococci are seen in a Gram stain of vaginal secretions, many of the bacteria inside polymorphonuclear leukocytes. Which of the following is the most important virulence factor necessary for this organism to initiate infection?

A) invasive genesi
B) pili
C) capsule
D) endotoxin
E) hyaluronidase 

Answer: B

(Year Posted:  UI 14)

 

Key Code: B

A NYC firefighter is severely burned while rescuing a child from a burning building. While hospitalized in the burn center of your hospital he develops a necrotic, rapidly disseminating bacterial infection in a burn wound. Within hours he becomes agitated and quite confused. By this time his temperature has fallen to 35oC and his blood pressure has fallen considerably. Culture of the infected area and blood cultures yield colonies producing a green pigmentation on the agar. These colonies contain cells that are oxidase positive, Gram-negative rods that can grow at 42oC.

Which of the following statements MOST ACCURATELY conveys information about this organism?

A) These bacteria are among the most antibiotic resistant of medically relevant bacteria
B) Capsules are the only known virulence factor for these bacteria
C) Humans are the only known reservoir for these bacteria
D) These bacteria grow best at 25oC
E) These bacteria exhibit a special kind of motility called swarming

Answer: A

(Year Posted:  UI 15)

 

Key Code: B

Which of the following antibiotics would likely be MOST EFFECTIVE against this organism?

A) penicillin G
B) penicillin V
C) ampicillin
D) ampicillin + clavulanate
E) piperacillin
F) methicillin

Answer: E

(Year Posted:  UI 16)

 

Key Code: B

Which of the following MOST ACCURATELY describes the mechanism one of the most important virulence factors encoded by this organism?

A) paralysis of cilia by crosslinks
B) ADP ribosylation of a G-regulatory protein
C) ADP-ribosylation of EF2
D) ADP ribosylation of microfilament cytoskeletal components

Answer: C

(Year Posted:  UI 17)

 

Key Code: B

Which of the following bacteria are also commonly associated with wound infections of this type?

A) Streptococcus pyogenes
B) Staphylococcus aureus
C) Staphylococcus epidermidis
D) Clostridium tetani
E)  Bacillus anthracis

Answer: B 

(Year Posted:  UI 18)

 

Key Code: M, Key Code: B

Soon after being administered an intravenous (IV) glucose solution, a hospitalizedpatient developed a fever. The solution had been appropriately autoclaved before use and the IV lines had been sterilized with ethylene oxide. A reasonable suspicion is that:

A) The solution was contaminated by bacterial spores
B) The IV lines were contaminated by mycobacteria
C) The solution was contaminated with heat-resistant gram negative bacterium
D) The IV lines were contaminated with a gram positive bacterium
E)  The solution was contaminated with pyrogen

Answer: E

(Year Posted:  UI 19)

        

Key Code: F

Candida albicans colonizes a variety of mucosal surfaces, where it may cause disease if its overgrowth is permitted (e.g., by broad spectrum antibacterial use or immunosuppression). The ability of C. albicans to colonize mucosal surfaces was recently shown to be enhanced by:

A) Filamentous hemaglutinin (Fha)
B) Mannose-binding pili (adhesins)
C) Polysaccharide capsule binding of host fibronectin
D) Receptors for neuraminic acid
E) Transglutaiminase-catalyzed crosslinking of hyphal wall protein

Answer: D

(Year Posted: UI 20)

 

Key Code: B

A 62-year-old man with diabetes presents with abdominal cramps, diarrhea and difficulty in breathing. Chest X-ray reveals bilateral infiltration. Poorly stained, gram-negative rods were seen in the sputum. A pure culture grew on buffered charcoal yeast extract agar. This organism also causes:

A) Pontiac fever
B) Q fever
C) Rheumatic fever
D) Scarlet fever
E) Valley fever

Answer: A 

(Year Posted:  UI 21)

 

Key Code: F

A 56-year-old female with acute lymphoid leukemia became neutropenic after chemotherapy. She subsequently developed bilateral pulmonary infiltrates, which on biopsy revealed septate hyphae with acute-angle branching. On the basis of this, you presumptively identify the pathogen as:

A) Aspergillus sp
B) Histoplasma capsulatum
C) Mucor sp
D) Mycobacterium avium-intracellulare
E) Mycoplasma pneumoniae

Answer: A 

(Year Posted:  UI 22)

 

Key Code: P, Key Code: B

A 12-year-old girl presented with a two-week history of headache, fever, sore throat and persistent cough. Chest X-ray showed areas of patchy infiltration. The two organisms MOST LIKELY to cause this illness include:

A) Chlamydia pneumoniae and Coccidioides immitis
B) Chlamydia pneumoniae and Mycoplasma pneumoniae
C) Legionella pneumophila and Streptococcus pneumoniae
D) Streptococcus pneumoniae and Mycobacterium tuberculosis

Answer: B 

(Year Posted:  UI 23)

 

Key Code: F

A 20-year-old male, a resident of a rural Indiana town, was admitted to a local hospital with fever, cough, and enlargement of the lymph nodes. Chest X-ray showed a pattern resembling primary tuberculosis. Sputum cultures revealed mycelial growth when incubated at room temperature, and tuberculate macroconidia were observed under the microscope. Culture at 37oC revealed slow-growing yeast. The infection is MOST LIKELY due to:

A) Aspergillus fumigatus
B) Blastomyces dermatitidis
C) Candida albicans
D) Coccidioides immitis
E) Histoplasma capsulatum

Answer: E 

(Year Posted:  UI 24)

 

Key Code: B

A 2-month-old boy presented with a 10-day history of sore throat, fever, and profuse respiratory secretions. During the last three days, he developed a cough that progressively increased in frequency and forcefulness. His chest radiography was clear. His white blood cell was 17,700 cells/mm3 with 80% lymphocytes. Gram-negative coccobacilli were cultured on charcoal blood agar from a nasopharyngeal swab. The MOST LIKELY etiological agent is:

A) Bordetella pertussi
B) Corynebacterium diphtheriae
C) Klebsiella pneumoniae
D) Legionella pneumophila
E) Mycoplasm pnumoniae

Answer: A 

(Year Posted:  UI 25)

Key Code: B, Key Code: V, Key Code: F, Key Code: N

A 9-month-old male is referred to a pulmonologist due to failure to thrive and persistent cough. The child's mother comments that the child's skin is salty and that he has frequent, bulky, foul-smelling stools. A positive sweat test and genetic testing revealing a trinucleotide deletion in CF transmembrane regulator (CFTR) confirmed the diagnosis. As the child ages what organism is most likely to colonize his lower respiratory tract resulting bouts of difficult to treat pneumonia?

A) Haemophilus influenzae
B) Histoplasma capsulatum
C) Legionella pheumophilia
D) Mycobacterium capsulatum
E) Pseudomonas aeruginosa

Answer: E 

(Year Posted: UI 26)

 

Key Code: B

A 37-year-old male college student professor presents to the ER with seizures. For the past few days, he has been complaining of severe headaches. Neurological exam is unremarkable. A computed tomagraphy scan shows one ring-enhancing lesion. Brain biopsy reveals an abscess, which was surgically removed. Staining of the biopsy material revealed gram-positive filamentous organisms. A member from which two genera is MOST LIKELY responsible for the patient's abscess?

A) Actinomyces or Nocardia
B) Clostridium or Candida
C) Enterobacter or Actinomyces
D) Enterobacter or Mycobacterium
E) Histoplasma or Blastomyces
F) Klebsiella or Enterobacter
G) Nocardia or Mycobacterium

Answer: A 

(Year Posted: UI 27)

 

Key Code: B

Your patient is a 63-year-old man with colon cancer. Five days ago, he underwent surgery to remove a portion of his intestine affected by the cancer. He now has a high fever and severe abdominal pain. Exploratory laparotomy revealed peritonitis with multiple small abscesses. Culture of the abscess material revealed a mixed infection. The predominant organism isolated was an encapsulated, anaerobic gram-negative rod which:

A) Also causes peptic ulcer disease
B) Forms spores
C) Is frequently associated with septic shock
D) Is normal flora and is resistant to many antibiotics
E) Produces an enterotoxin

Answer: D 

(Year Posted: UI 28)

 

Key Code: B

A 32-year-old waitress developed an intra-abdominal infection following surgery to remove her gall bladder. After drainage of an abscess, you prescribed treatment with clindamycin for two weeks. On day 10 of antimicrobial therapy, she presented with a 3-day history of watery diarrhea and abdominal pain. Routine stool culture on MacConkey and EMB agar was unremarkable. However, the diagnosis was confirmed by the detection of both an enterotoxin (toxin A) and cytotoxin (toxin B) by ELISA in stool filtrates. The MOST LIKELY cause of her diarrhea is:

A) Bacteroides fragilis
B) Campylobacter jejuni
C) Clostridium difficile
D) Enteroinvasive Escherichia coli
E) Vibrio parahaemolyticus

Answer: C 

(Year Posted: UI 29)

 

Key Code: I

A patient became ill 10 days ago with a viral infection. The clinical laboratory did a passive hemagglutination assay to titer IgM and IgG to the virus. As is indicated below the plate, two-fold serum dilutions were plated from left to right. Positive and negative controls were included at the far right. If well number 1 quantitates anti-virion IgM and well number 2 quantitates anti-virion IgG, what is the BEST interpretation of this data?

 

 

 

 

 

 

 

A) The patient has an IgM anti-virus titer of 128
B) The patient has more IgG than IgM in his serum
C) The patient has mounted a normal secondary immune response to this organism
D) The patient is likely to have never seen this virus before this illness
E) The patient most likely has a B cell immunodeficiency

Answer: D 

(Year Posted: UI 30)

 

Key Code: I

A genetically modified mouse defective in B cell somatic hypermutation was created. The mouse was immunized subcutaneously with ovalbumin and sacrificed 10 days later. Anti-ovalbumin B cells clones were isolated from the draining lymph nodes. If a single VDJ gene rearrangement yielded multiple B cell clones, clones producing which isotype would bind most tightly to an ovalbumin aggregate?

A) IgE
B) IgG
C) IgM
D) Plasma IgA
E) Secretory IgA

Answer: C 

(Year Posted: UI 31)

 

Key Code: I

A 19-year-old African-American presents to her primary care physician with an extranodal mass involving the mandible. Biopsy revealed lymphoma cells with the following characteristics: germline TCR genes, sIgM-positive, sIgD-positive, CD19-positive, CD20-positive. What normal cell component markers are most similar to those expressed by the lymphoma cell?

A) Pre-B cell
B) Immature B cell
C) Mature B cell
D) Pre-T cell
E) Immature T cell
F) Mature T cell
G) Natural Killer cell

Answer: C

(Year Posted: UI 32)

 

Key Code: I

A 6-month-old male is brought to the clinic with a severe case of pneumonia. This is the second case of bacterial pneumonia in the last month for this infant. Laboratory results indicated that the baby has made extremely poor antibody responses against the childhood vaccines given thus far. Flow cytometry revealed the following plots for CD19 expression and HLA-DR expression on the baby's peripheral blood lymphocytes and on an age-matched (normal) control

 

Based on the data, which of the following statements best describes the mechanism and consequences of this child's immune abnormality?

 

 

 

 

 

A) A developmental block between pre B cells and immature B cells prevents the production of mature B cells
B) A T cell abnormality results in abnormal B cell function
C) The BCR cannot specifically bind antigen leading to antibody production
D) The lack of class II MHC and ensuing difficulties in T cell education lead to the lack of B cell help
E) The lack of TAP results in abnormal CD8+ T cell due to difficulties in T cell activation

Answer: D

(Year Posted:  UI 33)

 

Key Code: I, Key Code: M

Three days after an appendectomy, the patient develops high fever. The patient's vital signs include a fast weak pulse, rapid and shallow respiration, and dangerously low blood pressure. The patient's erythrocyte sedimentation rate (ESR) is very high. The incision site is tender, red, and seeping purulent fluid. Cultures from the incision site and the patient's blood grew a gram-negative rod. What immune mechanism is most likely responsible for the patient's symptoms?

A) Cytotoxic T cell killing at the site of the incision
B) Induction of agammaglobulinemia by the organisms
C) Inhibition of mononuclear cell chemotaxis
D) Overproduction of TNF-a by macrophages
E) Underproduction of IL-8 by neutrophils

Answer: D 

(Year Posted: UI 34)

 

Key Code: I

A three-year-old boy presents to his pediatrician's office with coughing, shortness of breath, and a fever. Because he has had a series of frequent, unusual, and severe bacterial infections, you order a series of tests to evaluate his immune function. Analysis of his lymphocytes reveals normal numbers of CD4+, CD8+, and CD19+ cells, and both his B cells and T cells are able to proliferate in response to Pokeweed mitogen (PWM). In addition, the following diagram was created by flow cytometric analysis.

This data suggests that the patient has an immunodeficiency, which would alter many immune functions. Which of the following functions would remain intact?

A) IgM production against childhood vaccines
B) NK cell mediated antibody dependant cellular cytotoxity (ADCC)
C) Normal bacterial surveillance in the issue
D) sIgA in the tears and saliva blocking pathogens at external surfaces and prevent infection
E) The capacity for hayfever

Answer: A

(Year Posted: UI 35)

 

Key Code: I, Key Code: M, Key Code: B

A 4-year-old girl is brought by her mother to the emergency room because she found her urinating in the hallway (not her usual behavior). Earlier that day she complained of not feeling well and took a nap. On physical examination, you discover a combative child minimally responsive to verbal stimuli. The patient's vital signs include a temperature of 39oC, a fast weak pulse, rapid and shallow respiration, and dangerously low blood pressure. Her ESR is very high. If you were to analyze her serum complement levels, what would you expect to see?

A) Decreased serum C3 and decreased C4 levels
B) Decreased serum C3 and normal C4 levels
C) Elevated C3 and C4 levels
D) Elevated CH50
E) Normal serum C3 and decreased C4 levels

Answer: B

(Year Posted: UI 36)

 

Key Code: I

A 26-year-old male, with significant cat allergies, visits a home with multiple cats. Two hours later, he arrives at an urgent care center with a severe exacerbation of asthma. He is treated with a short acting bronchodilator and epinephrine. Initially, after treatment, his symptoms resolved; however, 8 hours later he is forced to go the emergency room with another exacerbation. What is the MOST LIKELY cause of his symptoms?

A) Additional IgE cross-linking on mast cells leading to lipid mediator and cytokine release
B) CD4+Th1 cells production of IFN-g
C) Complement activation leading to mast cell degranulation by C5a and C3a
D) Eosinophil and basophil infiltration leading to the release of proinflammatory mediators
E) Macrophage chemotaxis and the release of superoxide radicals
F) Neutrophil recruitment and the release of cytoplasmic granule components

Answer: D

(Year Posted: UI 37)

 

Key Code: I

A line of tumor cells is injected into a host animal (assume the tumor was derived from another MHC matched animal). The tumor was destroyed within 5 days. When the animal was analyzed, it was discovered that the animal had a negligible CTL response against the tumor. Flow cytometry revealed that the tumor cells had very low levels of class I MHC expression. The BEST explanation for the destruction of the tumor cells is that:

A) Cytotoxic T lymphocytes had an MHC-induced alloreaction against the tumor cells
B) Cytotoxic T lymphocytes specific for the tumor antigens killed the tumor cells
C) Mast cells released histamine and other inflammatory mediators that clear the tumor
D) Natural killer cells bound anti-tumor antibodies and killed the tumor cells
E) Natural killer cells recognized the loss of class I MHC and killed the tumor cells
F) Neutrophils recognized C3b deposited on the surface of the cell via the alternative complement pathway and kill the tumor cells. 
G)The host animal made tumor specific antibodies that coated and lysed the tumor cells 

Answer: E 

(Year Posted: UI 38)

 

Key Code: I

Granulomas are formed by a combination of T cell cytokine production and macrophage accumulation and activation. Which macrophage product early in this process would promote the T cell cytokine profile leading to a granuloma?

A) IL-1
B) IL-6
C) IL-8
D) IL-12
E) TNF-a

Answer: D 

(Year Posted:UI 39)

 

Key Code: I, Key Code: N

A man who has been taking an over-the-counter preparation of chlorpheniramine to control his seasonal allergic rhinitis begins to experience dry mouth and blurry vision. He sees his physician who immediately takes the patient off the chlorpheniramine and prescribes an alternate medication, which controls his allergy symptoms without the unwanted side effects. Which of the following medications did the physician most likely prescribe?

A) cyclizine
B) cyproheptadine
C) diphenhydramine
D) fexofenadine
E) promethazine

Answer: D 

(Year Posted: UI 40)

 

INSTRUCTIONS:
Treatment of infections with more than one antimicrobial or antiviral drug is indicated under some circumstances. For the cases described in the next three questions, select the most important reason for using multi-drug therapy from the list below.

A) to achieve greater clinical efficacy against sensitive pathogens by using drugs with synergistic actions
B) to avoid selecting for the emergence of drug-resistant strains
C) to create a broader spectrum of activity than is possible with a single drug

Key Code: B, Key Code: N

A 30-year-old woman complains of urinary frequency and urgency, and a burning sensation on urination. Her urin analysis is notable for numerous white blood cells and bacteria.Escherichia coli is recovered from her urine culture. Her doctor prescribes sulfamethoxazole and trimethoprim.

Answer: A 

(Year Posted: UI  41)

Key Code: B, Key Code: N

A 20-year-old man is brought to the emergency department with a gunshot wound to the abdomen. Surgical exploration reveals a perforation of the colon and fecal material in the peritoneal cavity. After surgery, the patient is placed on a regimen of intravenous ciprofloxacin and metronidazole.

Answer: C 

(Year Posted: UI 42)

Key Code: V, Key Code: N

A 35-year-old man without abnormal signs or symptoms has a confirmed positive result on an HIV screening test. His viral load is 10,000 copies/ml and his CD4+ lymphocyte count is 900/ml. His doctor prescribes zidovudine, lamivudine, and ritonavir.

Answer: B 

(Year Posted: UI  43)

  

INSTRUCTIONS:
This case description applies to two following questions below.

A 50-year-old man with cirrhosis was stabbed in the abdomen. He was brought to the emergency room in distress. Abdominal examination showed an entrance wound near the umbilicus. His abdomen was tender and rigid. On exploratory laparotomy, there were multiple lacerations in his transverse colon and fecal material in the abdominal cavity

Key Code: B

Against what organisms should prophylactic antimicrobial therapy be directed?

A) Escherichia coli and Bacteroides fragilis
B) Haemophilus influenzae and Campylobacter jejuni
C) Klebsiella pneumoniae and Chlamydia trachomatis
D) Staphylococcus aureus and Streptococcus pyogenes

Answer: D 

(Year Posted: UI  44)

Key Code: B, Key Code: N

The most appropriate therapy would be

A) ampicillin and gentamicin
B) ceftriaxone and metronidazole
C) gentamicin and erythromycin
D) gentamicin and vancomycin

Answer: B 

(Year Posted:UI  45)

 

Key Code: M, Key Code: B, Key Code: N

The mechanism that causes bacteria to become tolerant to the effects of ampicillin will usually also result in tolerance to the effects of:

A) ciprofloxacin
B) gentamicin
C) sulfamethoxazole/trimethoprim
D) vancomycin

Answer: D 

(Year Posted: UI  46)

 

Key Code: M, Key Code: B, Key Code: N

How do extended-spectrum b-lactamases (ESBLs) originate?

A) by induction of normal chromosomal genes
B) by mutation of ordinary b-lactamase genes
C) by treatment with aminoglycosides
D) by treatment with extended-spectrum b-lactam antibiotics
E) by treatment with ordinary b-lactam antibiotics

Answer: B 

(Year Posted: UI 47)

 

Key Code: I

In which of these processes does DNA double-strand break repair occur?

A) class switching and differential splicing
B) class switching and somatic hypermutation
C) VDJ recombination and class switching
D) VDJ recombination and differential splicing
E) VDJ recombination and somatic hypermutation

Answer: C 

(Year Posted: UI  48)

 

Key Code: I

A one-year-old child with a history of recurrent diarrhea is admitted for bronchitis. She is determined to have profoundly depressed levels of circulating IgG, IgA, and IgM. FACS analysis of peripheral blood lymphocytes reveals that less than 1% are CD19+, but normal numbers of CD3+ cells and NK cells are present. A mutation in which gene is most likely responsible for her condition?

A) CD40L
B) Iga
C) MHC class II
D) RAG1
E) RAG2

Answer: B 

(Year Posted: UI 49)

 

INSTRUCTIONS:
Select the mechanism that best explains the observations..

A) conjugation followed by transformation
B) conjugation followed by transposition
C) generalized transduction
D) global activation
E) phase variation
F) repression
G) specialized transduction

Key Code: M

A Moraxella species can express either of two different pilin proteins, called a and b. When bacterial colonies expressing the a pilin are examined, 1 in 104 cells can be shown to express the b pilin. When bacterial colonies expressing the b pilin are examined, 1 in 104 cells can be shown to express the a pilin. The difference between cells expressing the a and b pilin appears to be associated with an inversion of about 2 kilobases of DNA, whose endpoints occur within the coding region of the expressed pilin gene.

Answer: E 

(Year Posted: UI  50)


Key Code: M

An epidemic strain of Salmonella typhimurium exhibits multi-drug resistance. The resistance genes are organized as integrons contained within the genome of a lysogenic bacteriophage. DNA sequence analysis of eight different isolates of this strain demonstrates that the prophage genomes are found at the same chromosomal location in each isolate.

Answer: G 

(Year Posted: UI  51)

 

Key Code: B

An elderly woman was brought to the emergency room complaining of blurred vision, and difficulty in swallowing and breathing. She displayed flaccid paralysis in the muscles of her neck and extremities. Before treatment could be initiated, the patient succumbed to respiratory failure. Her son revealed that the previous day (18 hours earlier), his mother had prepared bean salad from a jar of home-canned green beans. When a sample of the bean salad was cultured (both anaerobically and aerobically) to test for the presence of bacteria, no bacteria were found. What was the most likely cause of the patient's death?

A) botulinum toxin
B) Clostridium perfringens a toxin
C) lipopolysaccharide (LPS)
D) lipoteichoic acid (LTA)
E) staphylococcal enterotoxin
F) staphylococcal toxic shock syndrome toxin (TSST-1)
G) tetanus toxin
H) tetanus toxoid

Answer: A 

(Year Posted: UI 52)

 

Key Code: B

During a civil war, a country in northern Europe endures several years of widespread famine and economic hardship. There is also an outbreak of a severe, acute febrile illness with a rash, multiple organ-system involvement, and high mortality. The outbreak is mostly confined to the cities, which have grown more overcrowded and unsanitary than before. People who remain in, or flee to, the countryside are much less likely to be affected. What infectious disease is most likely to account for these observations?

A) ehrlichiosis
B) dengue
C) Lyme disease
D) Rocky Mountain spotted fever
E) typhus

Answer: E 

(Year Posted: UI 53)

 

Key Code: B

A moderately obese 45-year-old woman complains of right-upper-quadrant abdominal pain accompanied by flatulence. She is febrile, and Enterococcus faecalis is recovered from a blood culture. How was her infection most likely initiated?

A) by axonal transport
B) by hematogenous spread
C) by lymphatic spread
D) by the ascending route
E) by vector spread

Answer: D 

(Year Posted: UI 54)

 

Key Code: B, Key Code: V, Key Code: N

A common factor facilitating the re-emergence in the 1990s of measles in New York City and diphtheria in Russia was

A) governmental instability
B) inadequate immunization
C) increased injection drug abuse
D) microbial adaptation
E) the spread of HIV infection

Answer: B 

(Year Posted: UI 55)

 

Key Code: P

A medium-sized city in upstate New York experienced a malfunction in its water purification system. Over the next several weeks, there was a dramatic increase in visits to the emergency room for diarrhea. Several patients with AIDS developed severe diarrhea and died of dehydration. Which pathogen was most likely responsible for this outbreak?

A) Listeria species
B) Dengue fever virus
C) Cryptosporidium species
D) Clostridium botulinum
E) Cyclospora species

Answer: C 

(Year Posted: UI 56)

 

Key Code: I, Key Code: N

The induction of which factor or enzyme best accounts for the anti-inflammatory actions of glucocorticoids?

A) cyclooxygenase I (COX I)
B) cyclooxygenase II (COX II)
C) cytochrome P450 3A (CYP3A)
D) inhibitory factor kBa (IkBa)
E) nuclear factor kB (NF-kB)

Answer: D 

(Year Posted: UI 57)

 

Key Code: N

According to the Anderson-May model, if the reproductive rate of an infection is 5, what is the minimum percentage of immunes necessary to achieve herd immunity?

A) 50%
B) 75%
C) 80%
D) 90%
E) 95%

Answer: C 

(Year Posted: UI 58)

 

Key Code: V

In a person with HIV infection, which of the following conditions is suggestive of the greatest degree of immunosuppression?

A) cerebral toxoplasmosis
B) generalized lymphadenopathy
C) oral thrush
D) thrombocytopenia
E) vaginal candidiasis

Answer: A 

(Year Posted: UI 59)

 

Key Code: I, Key Code: V

Dengue hemorrhagic fever most frequently results from

A) infection of a non-immune patient
B) infection of a recovered dengue patient with a different viral strain
C) infection with a particular viral strain
D) reinfection of a recovered dengue patient with the same viral strain

Answer: B 

(Year Posted: UI 60)

 

Key Code: I

Lysis of red blood cells occurs in a complement fixation test when the patient's serum

A) contains complement C3
B) contains non-specific antibody
C) contains specific antibody
D) lacks complement C3
E) lacks specific antibody

Answer: E 

(Year Posted: UI 61)

 

Key Code: I, Key Code: V

A 61-year-old man was bitten by a mosquito and subsequently developed the symptoms of encephalitis. On admission to the hospital a serum specimen, the acute sample, was drawn. The patient recovered and one month later another serum sample, the convalescent specimen, was drawn. Complement fixation tests using his serum and West Nile virus were performed. The acute phase serum gave a titer of 1:8 and the convalescent serum gave a titer of 1:4. What is the most likely conclusion that can be drawn from these observations?

A) The data are inconclusive
B) The patient probably did not have West Nile virus encephalitis
C) The patient probably had West Nile virus encephalitis
D) The patient probably has a complement deficiency

Answer: B 

(Year Posted: UI 62)

 

Key Code: I, Key Code: B, Key Code: N

A lymph node biopsy shows multiple necrotizing ("caseating") granulomas. A culture of material obtained at the time of biopsy grows Mycobacterium tuberculosis. Which substance produced locally is the principal activator or stimulator of monocytes and macrophages?

A) bradykinin
B) interferon g 
C) leukotriene B4
D) prostaglandin E2
E) the trimolecular complex (C567)

Answer: B 

(Year Posted: UI 63)

 

Key Code: B, Key Code: N

A 40-year-old man previously in good health presents with cough and high fever of eight days duration. Staphylococcus aureus grows in his sputum and blood cultures. The chest x-ray is read by the radiologist as follows: "well-circumscribed rounded cavitary lesion in the right lower lobe with fluid contents and an air-fluid level." Which one of the following descriptions best characterizes the inflammatory response at this time?

A) abscess formation
B) cellulitis 
C) complete resolution
D) necrotizing granulomatous inflammation

Answer: A 

(Year Posted: UI 64)

 

Key Code: I, Key Code: M, Key Code: V

At intervals of one to several decades, an Influenza A subtype that has been absent or nearly absent from human populations suddenly becomes widely circulating, frequently leading to a pandemic. This is caused by

A) bioterrorism
B) genetic drift
C) genome segment reassortment
D) global climatic change
E) point mutation 
F) the hibernation pattern of the virus' non-human host 

Answer: C 

(Year Posted: UI 65)

 

Key Code: I, Key Code: M

In adults, lactic acid production by lactobacilli is an important contribution to the antimicrobial defenses of the

A) blood
B) colon
C) mouth
D) nose
E) skin 
F) vagina 

Answer: F 

(Year Posted: UI 66)

 

Key Code: I

The most likely reason for a lung allograft to undergo immune mediated rejection at three weeks post transplantation is

A) activation of T lymphocytes via the direct pathway
B) activation of T lymphocytes via the indirect pathway
C) a hyperacute rejection reaction
D) an ABO mismatch
E) antibody-dependent cell-mediated cytotoxicity (ADCC) 

Answer: A 

(Year Posted: UI 67)

 

Key Code: V

A child suffers an acute febrile illness accompanied by altered mental status and other signs of central nervous system involvement. She recovers spontaneously without sequelae. The causative agent is a naked virus. How was it most likely acquired?

A) ingestion
B) inhalation
C) skin penetration
D) vector spread

Answer: A

(Year Posted: UI 68)

 

Key Code: I

An individual with a defect in CTLA-4 will be most likely to have which of the following?

A) Type I hypersensitivity
B) immunodeficiency
C) recurrent Neisseria infections
D) lymphoproliferative disease

Answer: D 

(Year Posted: UI 69)

 

Key Code: I

The class of immunity generated against a particular pathogen is determined by the cytokines present in the environment. Which of the following combinations of cytokines will lead to a response that is appropriate against a virus infection?

A) IL-4, IL-10, and IFNg
B) IL-12 and IFNg
C) IFNg, IL-2, and TNFb
D) IL-4, IL-5, and IL-10

Answer: B 

(Year Posted: UI 70)

 

Key Code: I

Once a TH1 or TH2 response has been generated, it is perpetuated by cytokines that down regulate the opposing response. If a humoral response has been stimulated, which cytokines will maintain that response?

A) IL-4 and IL-10
B) IL-4 and IL-5
C) IL-4 and TNFb
D) IL-1 and IL-6

Answer: A 

(Year Posted: UI 71)

 

Key Code: I

Positive selection in the thymus occurs when:

A) selectins, addressions or integrins bind to appropriate receptors and remain in the thymus
B) T cells that recognize an antigen present in the thymus are stimulated to divide
C) T cells that see MHC with an intermediate affinity are selected to survive
D) T cells that see self antigen are killed by apoptosis

Answer: C 

(Year Posted: UI 72)

 

Key Code: I

The molecules involved in signal transduction when antigen binds to the B cell receptor are:

A) the CD3 complex
B) CD19 and CD20
C) gdezz or gdezn 
D) Iga and Igb

Answer: D 

(Year Posted: UI 73)

 

Key Code: I

Gene rearrangement leads to the development of antigen specific receptors on which of the following cells?

A) NK cells, ADCC, and CTL
B) B cells
C) B cells and CTL
D) CTL, DTH and Helper T cells
E) B cells, CTL, DTH and Helper T cells
F) B cells and Macrophages
G) B cells, CTL, DTH, Helper T cells and macrophages

Answer: E 

(Year Posted: UI 74)

 

Key Code: I

TAP proteins are involved in:

A) MLR reactions
B) antibody production
C) the classical complement pathway
D) presentation of peptides by Class I MHC
E) presentation of peptides by Class II MHC

Answer: D 

(Year Posted: UI 75)

 

Key Code: I

Which combination of the following would be sufficient to indicate that an individual has AIDS?

A) a positive ELISA for antibodies against HIV
B) a positive HIV ELISA for HIV antibodies and more than two positive bands in a confirmatory Western blot analysis
C) both A and B and a CD4 count greater than 400 cells/ul 
D) both A and B and a CD4 count less than 200 cells/ul

Answer: D

(Year Posted: UI  76)

 

Key Code: I

In the serum of most normal individuals the class of immunoglobulin that increases in a chronic infection is:

A) IgM
B) IgA
C) IgE 
D) IgG
E) IgD

Answer: D

(Year Posted: UI  77)

 

Key Code: I

Serum from a patient is analyzed by serum protein electrophoresis. The gamma globulin peak is twenty times lower than that of a normal healthy individual.

A) this result is normal because not all people have similar levels of IgG
B) this result may indicate a B cell immunodeficiency
C) this patient probably has an autoimmune disease
D) the patient may have a myeloma protein

Answer: B 

(Year Posted: UI  78)

 

Key Code: I

Two patients with SLE are tested for antibodies to double stranded DNA. One has a titer of 40, the other a titer of 1280. Who is most likely to show the signs of an exacerbation of this disease?

A) the patient with a titer of 40
B) the patient with a titer of 1280

Answer: B

(Year Posted: UI  79)

 

Key Code: I

A patient with active rheumatoid arthritis feels systemically ill with low grade fever, malaise, morning stiffness and fatigue. The protein(s) or cytokine(s) most likely to be responsible for these symptoms are:

A) Rheumatoid factor
B) IL1 and TNF
C) IL4 and IL10
D) C1 - C9
E) altered gamma globulin

Answer: B

(Year Posted: UI  80)

 

Key Code: I

One of the most important cytokines in the non-specific activation of macrophages as effector cells of delayed-type hypersensitivity is:

A) IL1
B) IFNg?
C) TNFa?
D) MCF

Answer: B

(Year Posted: UI  81)

 

Key Code: I

Bob is allergic to ragweed pollen. He has been treated with ragweed pollen allergen using a minute concentration and gradually increasing doses repeatedly for desensitization (hyposensitization) therapy to reduce the allergic reaction. Hyposensitization probably operates using which of the following principles?

A) clearance of antigen-specific IgE immune complexes
B) greater production of circulating high affinity IgG antibody
C) depletion of the mast cell pool by repeated degranulation
D) specific tolerance induction

Answer: B

(Year Posted: UI  82)

 

Key Code: I

A hypothetical immunoglobulin, IgH, has 3 constant domains on its heavy chain and a molecular weight of 300,000. What is its probable valence?

A) 2
B) 4
C) 5
D) 10

Answer: B

(Year Posted: UI  83)

 

Key Code: I

In B cell development when the heavy first rearranges it may be expressed on the B cell prior to light chain rearrangement. If this is the case, the heavy chain is associated with which of the following peptides on the surface of the cell?

A) invariant light chain
B) surrogate light chain
C) CLIP
D) it isn't associated with anything

Answer: B

(Year Posted: UI  84)

 

Key Code: I

A dendritic cell in an individual who has the flu is infected with virus A. Dendritic cells in this individual would be expected to have which of the following antigens on their surface?

A) Class II with flu peptides and peptides from virus A. Peptides of virus A will also be the binding cleft of Class I
B) Peptides of virus A will be the binding cleft of Class I. Neither virus will be presented by Class II
C) Class I with flu peptides and peptides from virus A
D) Class II with flu peptide and peptides from virus A

Answer: A 

(Year Posted: UI  85)

 

Key Code: I

Which of the following clinical methods could be used to determine whether or not a potential bone marrow recipient has preformed antibodies to the donors bone marrow stem cells?

A) Ouchterlony
B) immunoelectrophoresis
C) flow cytometry
D) hemagglutination

Answer: C 

(Year Posted: UI  86)

 

Key Code: I

These results were seen in a Mixed Lymphocyte Culture:

        Cells                 counts per minute

A + irradiated B                 15,000
A alone                              2,000

They indicate that:

A) A and B share all Class I MHC alleles
B) A and B have at least some differences in Class I MHC alleles
C) A and B share all Class II MHC alleles
D) A and B have at least some differences in Class II MHC alleles

Answer: D 

(Year Posted: UI  87)

 

Key Code: I

RANTES, MIP-1a? and MIP-1b? are important to scientists who study HIV because:

A) they are chemokines that bind to HIV gp120 and facilitate cell entry
B) they are chemokines that bind to CCR5, a co-receptor for HIV
C) they are cytokines that activate macrophages and enable HIV infection
D) they are cofactors that work with HIV to kill CD4 T cells

Answer: B 

(Year Posted: UI  88)

 

Key Code: I

Paul is infected with HIV and in fact has AIDS. His T cell count was less than 200 cells/ul but after treatment with HAART he is doing much better. What clinical picture would be possible after 5 months on HAART?

A) his viral load is undetectable and his CD4 cells counts are 400 cells/ul
B) his specific immune response to HIV has returned and he has resumed the battle against HIV
C) he has begun to clear HIV from the reservoirs of sequestered cells and may eventually eliminate the virus from his system
D) all of the above

Answer: A 

(Year Posted: UI  89)

Key Code: M

Tuberculosis was one of the major infectious diseases associated with fatality in the 19th and the early part of the 20th century. Which of the following measures was most important in bringing it under control at the end of the first half of the 20th Century, such that the TB mortality dropped to a quarter of the 1945 level by 1955?

A) Antibiotics
B) Antibody therapy
C) Quarantine of all carriers
D) Strict control on immigration
E) Vaccination

Answer: A 

(Year Posted: UI 90)

 

Key Code: M, Key Code: V, Key Code: P, Key Code: N

Though the crude rate from infectious diseases in the USA has decreased substantially since the start of the 20th century, there have been two times when the crude death rate has increased significantly. One was a massive increase in 1918-1920 and another was seen in the mid-late 1980's and 1990's. What were the causes of the two epidemics?

A) Influenza and AIDS
B) Malaria and tuberculosis
C) Syphilis and AIDS
D) Syphilis and poliomyelitis
E) Tuberculosis and AIDS

Answer: A 

(Year Posted: UI 91)

 

 Key Code: V

The capsid of a virus is composed of:

A) carbohydrate
B) deoxynucleic acid
C) lipid
D) protein
E) ribonucleic acid

Answer: D 

(Year Posted: UI 92)

 

Key Code: I

Which type of cell is characterized by responding to antigen when presented as a peptide in the groove of an MHC class II molecule?

A) CD4+ T cell
B) CD8+ T cell
C) Cytotoxic T cell
D) Mast cell
E) All of the above (A-D)

Answer: A 

(Year Posted: UI 93)

 

Key Code: I

Which cell type secretes IgE?

A) CD8+ cell
B) Mast cell
C) Plasma cell
D) Pre B cell
E) T cell

Answer: C 

(Year Posted: UI 94)

 

Key Code: I

Evaluate the following statement. "T cells differ from B cells in having several, structurally distinct, antigen receptors on any one cell.  This allows a T cell to respond to several different antigens."

A) True all the time
B) True usually (around 2/3 of the time
C) True about 1/3 the time
D) Not true

Answer: D 

(Year Posted: UI 95)

 

Key Code: M, Key Code: B

The gas forming the bubbles in the catalase reaction is:

A) hydrogen
B) methane
C) carbon dioxide
D) carbon monoxide
E) oxygen

Answer: E 

(Year Posted: UI 96)

 

Key Code: V, Key Code: N

Mrs. Gaither, 68 years old, goes to the doctor's office because her husband was hospitalized yesterday for complications of influenza (type A). She has chronic asthma, allergy to strawberries and has not received any vaccinations this year. She has breakfast with a friend and, while eating her eggs and toast, she hears that this friend had a "bad case of the flu" following influenza vaccination. Which of the following is correct?

A) Mrs. Gaither should receive both the influenza vaccine and influenza antivirals
B) Influenza vaccines can cause influenza and therefore a person in Mrs. Gaither's condition (chronic lung disease) is not a candidate for the vaccine
C) Amantadine and rimantidine are only effective against Influenza B and therefore Mrs. Gaither should not receive these
D) Mrs. Gaither will not get influenza because she will have immunity from her prior exposures to the virus over the last 50-60 years

Answer: A 

(Year Posted: UI 97)

 

Key Code: B

Streptococcus pyogenes group A can cause a number of post-infection sequelae. Which condition is observed after a throat infection, but not after a skin infection?

A) Glomerulonephritis
B) Psoriasis
C) Rheumatic heart disease
D) Schizophrenia

Answer: C 

(Year Posted: UI 98)

 

Key Code: I

When the sequences of different MHC class I molecules are compared, the variation between molecules is concentrated within which of the following?

A) Areas of the molecule that bind CD4
B) Areas of the molecule that bind to the TCR and bind the antigenic peptide
C) CD3 zeta chain
D) Transmembrane domain of the a chain
E) b1 domain (the N terminal domain of the beta chain)
F) b2-microglobulin

Answer: B 

(Year Posted: UI 99)

 

Key Code: I

Which of the following is NOT encoded within the MHC?

A) b2-microglobulin
B) HLA-C a-chain
C) HLA-DR a-chain
D) TAP1:TAP2 peptide transporter
E) Tumor necrosis factor-alpha (TNF-a)

Answer: A


(Year Posted: UI  100)

 

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AMSMIC is the Association of Medical School Microbiology and Immunology Chairs

Webmaster

 Multiple Choice Questions 101-200

Key Code: I

The typical multiple myeloma cell population is found to excrete:

A) a single immunoglobulin structure where all the antigen-binding regions are identical
B) all the isotypes of the Ig heavy (H) chain
C) all the isotypes of the Ig light (L) chain
D) immunoglobulins with more than one structure for the antigen-binding region occurring on a single molecule
E) many distinct immunoglobulin molecules, each with a different amino acid sequence within the variable regions of the H and L chains.

Answer: A 

(Year Posted:UI  101)

 

Key Code: V, Key Code: N

Which of the following is a contraindication for MMR vaccination?

A) Down's syndrome
B) hay fever
C) migraines
D) pregnancy
E) stress

Answer: D 

(Year Posted: UI  102)

 

Key Code: V

The following terms are used for describing features of measles and measles vaccination. Which is correctly paired with its description/definition?

A) Coryza - Acute laryngitis together with middle ear inflammation
B) Intravenous - Route for immunization with MMR
C) Koplik's spots - Exanthem
D) MMR Vaccine - which is composed of inactivated (dead) viral particles
E) Prodrome - Stage when patient is ill but rash has not appeared

Answer: E 

(Year Posted: UI  103)

 

Key Code: M, Key Code: B

Which of the following features of the agar is correct for the type of hemolysis seen around bacteria growing on a blood agar plate?

a hemolysisb hemolysisg hemolysis

A)

green

clear zones

no hemolysis

B)clear zonesgreenno hemolysis

C)greenno hemolysisclear zones

D)clear zonesno hemolysisgreen

E)no hemolysisclear zonesgreen

Fno hemolysisgreenclear zones


Answer: A 

(Year Posted: 2001 UI  104)

 

Key Code: B, Key Code: M

Identify the correct order for adding reagents in the Gram stain

 

Step 1Step 2Step 3Step 4A)

Iodine

Crystal Violet

Destain

Safranin

B)IodineSafraninCrystal VioletDestain

C)IodineDestainSafraninCrystal Violet

D)

Iodine

Crystal Violet

SafraninDestainE)

None of the above (A-D)


Answer: E 

(Year Posted: UI 105)

 

Key Code: I

During the development of B-2 cells, which immunoglobulin chain is the first to be expressed on the cell surface?

A) delta(d)
B) epsilon((e)
C) gamma((g)
D) kappa((k)
E) mu (m)

Answer: E 

(Year Posted: UI  106)

 

Key Code: I, Key Code: B, Key Code: N

A patient presents with his fifth neisserial infection (i.e. infection caused by a species of Neisseria) in 4 months. A measurement of total hemoltytic complement activity reveals non-detectable activity. This picture is most consistent with:

A) C1 inhibitor deficiencies
B) C6 deficiency
C) DAF defect
D) Factor B deficiency
E) Overexpression of C

Answer: B 

(Year Posted: UI  107)

 

Key Code: I

NK cells kill virally-infected cells that express:

A) elevated levels of MHC class II
B) reduced levels of MHC class I
C) IL-12 receptors
D) T cell receptors
E) CR4

Answer: B 

(Year Posted: UI  108)

 

Key Code: F

Which of the following does NOT cause ringworm?

A) Epidermophyton floccosum
B) Malassezia furfur
C) Microsporum audouinii
D) Trichophyton mentagrophytes
E) Trichophyton rubrum

Answer: B 

(Year Posted: 2001 UI  109)

 

Key Code: F

Candida parapsilosis is a clinically significant species of Candida. It produces:

A) germ tubes in germ tube broth
B) chlamydospores on corn meal agar
C) pseudohyphae
D) all of the above

Answer: C 

(Year Posted: UI  110)

Key Code: F

A lady stabbed her finger on a rose thorn while pruning back the rose bushes in her yard. Two weeks later, a very painful infected finger was observed and did not get better when she was treated with antibacterial antibodies. In fact, 3 weeks later, not only was the finger swollen, but painful red nodules were seen running up her arm along the lymphatic drainage vessels. Of the following, which is most likely the cause of the disease?

A) Amanitin poisoning
B) Malassezia furfur
C) Microsporum caris
D) Sporothrix schenckii
E) Trichophyton rubrum

Answer: D 

(Year Posted: UI  111)

 

Key Code: F

Which medium is used to cultivate the etiologic agent of tinea versicolor?

A) Bird seed agar
B) Sabouraud agar lacking glucose
C) Sabouraud agar supplemented with lipid
D) All are used (A-D)

Answer: C 

(Year Posted: UI  112)

 

Key Code: F

In order to identify the species of a dermatophyte that is causing tinea corporis in a wrestler, you need to:

A) cultivate the fungus and examine the structure of its anamorph
B) incubate the culture at 37°C to make sure the fungus develops quickly
C) perform a KOH mount showing hyphae and arthroconidia
D) perform the germ tube test
E) all of the above (A-D)

Answer: A 

(Year Posted: UI  113)

 

Key Code: F

Both Coccidioides immitis and Blastomyces dermatitidis:

A) are dimorphic fungi that grow as yeasts when in the lung
B) are largely restricted to persons who have lived in or visited tropical regions
C) cause pulmonary infections, but the fungus does not disseminate from the lung
D) regularly cause disease in immunocompetent persons
E) All of the above (A-D) are true of both fungi

Answer: D 

(Year Posted: UI  114)

 

Key Code: F

Fungal hyphae differ from yeasts in that hyphae have:

A) an apical growth pattern that leads to development of mycelium
B) extracellular enzymes
C) mitochondria
D) nuclei
E) ribosomes

Answer: A 

(Year Posted: UI  115)

 

Key Code: F

Wood's Light, which is used to detect fungal and some bacterial infections of skin, is a form of:

A) green visible light
B) infrared light
C) light coming from conventional fluorescent light tubes, e.g. those found in offices
D) near U.V. light
E) X-irradiation

Answer: D 

(Year Posted: UI  116)

 

Key Code: F

Round, naturally melanized (i.e., brown-pigmented) cells in human tissue represent the invasive form of the mold(s) in:

A) chromomycosis
B) ringworm
C) sportrichosis
D) tinea versicolor
E) all of the above (A-D)

Answer: A 

(Year Posted: UI  117)

 

Key Code: F

Which of the following is typical for the most deadly mushrooms, as opposed to those poisonous mushrooms that are not so serious? The most deadly mushrooms, such as those containing cyclopeptide toxins:

A) are restricted to the tropics
B) have a much more rapid onset of symptoms following ingestion
C) have longer incubation periods between eating and onset of symptoms
D) induce perspiration, salivation and lacrimation together with pinpoint pupils
E) taste bad, even to those who like mushrooms

Answer: C 

(Year Posted: UI  118)

 

Key Code: N, Key Code: F, Key Code: P

What is the meaning of "ptosis"?

A) A fungus ball in the lung
B) A zygomycete infection of the lung first described by Ptolemy
C) Drooping upper eyelid
D) Extensive infection of the dry skin and nails by Candida albicans
E) Infection derived from fungi colonizing intravenous catheters
F) Psychiatric disorder characteristically associated with sniffing bird guano and animal fecal materials
G) Vaginitis and concurrent inflammation of the uterus and Fallopian tubes

Answer: C 

(Year Posted:  UI  119)

 

Key Code: B

The infectious dose for a Shigella infection is 1,000,000 times lower than the infectious dose for a Salmonella infection because:

A) Salmonella is an invasive pathogen
B) Salmonella is more resistant to basic conditions
C) Shigella can attach to epithelial cells
D) Shigella is more resistant to acidic conditions
E) Shigella produces a more potent toxin

Answer: D 

(Year Posted: UI  120)

 

Key Code: F, Key Code: N

Which of the following diseases is strongly associated with diabetes?

A) Allergic bronchopulmonary aspergillosis
B) Aspergilloma
C) Invasive candidiasis of the kidneys
D) Mucosal candidiasis
E) Pneumocystosis

Answer: D 

(Year Posted: UI  121)

 

Key Code: B

Which of the following genera includes species that cause dysentery?

A) Campylobacter
B) Pneumocystis
C) Salmonella
D) Shigella
E) Vibrio

Answer: D 

(Year Posted: UI  122)

 

Key Code: F, Key Code: N

Which of the following findings are the best signs that a person is mounting an effective defense against disseminated histoplasmosis and is likely to recover from the infection?

A) Formation of a strong DTH skin test and rising titers of CF antibodies
B) Formation of a strong DTH skin test and low titers of CF antibodies
C) Transition from a strong to weak DTH skin test and rising titers of CF antibodies
D) Transition from a strong to weak DTH skin test and low titers of CF antibodies

Answer: B 

(Year Posted: UI  123)

 

Key Code: F

BOTH Candida tropicalis and Candida kefyr produce:

A) Chlamydospores
B) Germ tubes when incubated in germ tube broth
C) Yeasts
D) All of the above (A-C)

Answer: C 

(Year Posted: UI  124)

 

Key Code: F

Bird guano-contaminated soils and bat-feces are typical environmental sources for:

A) Aspergillus fumigatus
B) Candida albicans
C) Coccidioides immitis
D) Cryptococcus neoformans var. gattii
E) Histoplasma capsulatum

Answer: E 

(Year Posted: UI  125)

 

Key Code: F

Desert soils containing a high borate concentration in the Southwest of the USA are a typical source for:

A) Aspergillus fumigatus
B) Candida albicans
C) Coccidioides immitis
D) Cryptococcus neoformans var. gattii
E) Histoplasma capsulatum

Answer: C 

(Year Posted: UI  126)

 

Key Code: I, Key Code: N

What is the deficiency found in chronic granulomatous disease?

A) A reduced amount of IgM
B) A total lack of IgA
C) Deficiency of hydrogen peroxide and superoxide production by phagocytes
D) Failure to mount an antibody response to pyogenic bacteria
E) Failure to produce lymphocytes

Answer: C 

(Year Posted: UI  127)

 

Key Code: F

Which of the following would be very rare as an invasive infection in the early stages of AIDS but not unexpected in a person with chronic granulomatous disease?

A) Aspergillus fumigatus
B) Histoplasma capsulatum
C) Coccidioides immitis
D) Cryptococcus neoformans
E) Failure to produce lymphocytes

Answer: A 

(Year Posted: UI  128)

 

Key Code: B, Key Code: N

Which of the following predisposes to Pseudomonas aeruginosa infection?

A) Immunosuppression
B) Dehydration
C) Unprotected sex
D) Smoking
E) Anemia

Answer: A 

(Year Posted: UI  129)

 

Key Code: I

Which of the following statements is NOT true of the basophil?

A) It has surface receptors for IgE
B) It is derived from bone marrow precursors
C) It is more avidly phagocytic than the neutrophil
D) It releases histamine upon appropriate stimulation
E) It shares many functions with the mast cell

Answer: C 

(Year Posted: UI  130)

 

Key Code: I

Choose the answer that contains terms that correctly complete the sentence. Allergic individuals have a tendency to respond to antigens with a 1 -type response which includes the production of IL-4 and 2 , cytokines which are essential for maturation of eosinophils and induction of an IgE response to antigen.

 

 1 2A)

TH1

IFN-g

B)TH1IL-2

C)TH2IFN-g

D)

TH2

IL-5


Answer: D 

(Year Posted: UI  131)

Key Code: P

Ingestion of which of the following is MOST likely to lead to cysticercosis?  (Taenia solium is known as the pork tapeworm and Taenia saginata is known as the beef tapeworm.)

A) Taenia saginata eggs in salads
B) Taenia saginata eggs present in undercooked pork
C) Taenia saginata larvae present in undercooked beef
D) Taenia solium eggs contaminating salads
E) Taenia solium larvae in undercooked pork
F) Taenia solium larvae in undercooked beef 

Answer: D 

(Year Posted: UI 132)

 

Key Code: I, Key Code: P, Key Code: N, Key Code: F, Key Code: V

Atopic persons (i.e. those with atopy) are:

A) completely resistant to infection by Coccidioides immitis
B) deficient in production of IL-4
C) extremely susceptible to invasive candidiasis
D) predisposed to develop IgE-mediated allergic responses
E) those persons who harbor, at the time of establishment of the condition, more than one tapeworm
F) those persons who lack a chemokine receptor and so do not develop AIDS 

Answer: D 

(Year Posted: UI 133)

 

Key Code: F

Many fungi can invade neutropenic patients, but of all the molds, Aspergillus fumigatus predominates.  Which of the following provides a correct description for this fungus or invasive  aspergillosis?

A) If invasive aspergillosis is suspected, a blood specimen should be cultured as absence of the fungus in the culture would almost certainly rule out Aspergillus fumigatus as the etiologic agent
B) Sporangiospores are the infectious form of the fungus
C) The typical histological picture of invasive aspergillosis is the finding of septate hyphae that branch at an approximately 45º angle
D) The most common source for infectious fungus is its growth on tips of contaminated intravenous catheters
E) There is a strong tendency for Aspergillus fumigatus to cause rhinocebral infections in persons with diabetic ketoacidosis 

Answer: C 

(Year Posted: UI 134)

 

Key Code: F

Which of the following provides the most specific way of identifying a yeast as being Candida parapsilosis?

A) Creating a metabolic profile (based on the assimilation of various compounds as sole source of carbon or nitrogen, growth at various, temperatures etc.)
B) Failure to produce germ tubes
C) Formation of yeasts and pseudohyphae but no germ tubes in culture
D) Formation of yeasts in culture
E) Production of chlamydospores 

Answer: A 

(Year Posted: UI 135)

 

Key Code: P

Which of the following correctly describes giardiasis (Giardia lamblia)?

A) Disease is caused by a fluke
B) Infection is transferred via the bite of ticks
C) It is typically associated with an acute diarrhea that resolves within 2 days
D) It is characterized by constipation
E) There is production of foul-smelling feces because of malabsorption 

Answer: E 

(Year Posted: UI 136)

 

Key Code: P

Which of the following is correct concerning ascariasis (Ascaris lumbricoides)?

A) Only eggs in newly deposited human feces are infectious as, after 12 to 48 hours in the environment, the eggs will die
B) The adult is readily visible without the need of a magnifying glass or microscope
C) The eggs hatch in the small intestine and the larvae remain within the small and the large intestines while they fully mature into adults
D) The worm has a intermediate host which is a snail
E) All of the above are correct (A-D) 

Answer: B 

(Year Posted: UI 137)

 

Key Code: P

Which of the following lays eggs in tunnels within the epidermis?

A) Crab louse
B) Head louse
C) Hookworm
D) Pinworm
E) Scabies mite 

Answer: E 

(Year Posted: UI 138)

 

Key Code: P

The major cause of inflammation and fibrosis in schistosomiasis caused by Schistosoma mansoni is a   reaction to:

A) adult flukes in blood vessels
B) blockage of blood vessels by proglottids
C) dead eggs in tissues
D) dead tissue which has accumulated because of the profound anemia leading to ineffective oxygenation
E) inability of schistosomula to mature following infection of humans 

Answer: C 

(Year Posted: UI 139)

 

Key Code: P

Many parasites can be detected by finding eggs in freshly obtained human feces.  For which of the following, is this an appropriate, and routinely applied, diagnostic method? (Choose the one best answer)

A) Crab lice
B) Filariasis
C) Pinworm
D) Schistosomiasis
E) Strongyloidiasis 
AB Trichinosis 

Answer: D 

(Year Posted: UI 140)

 

Key Code: P, Key Code: I

Development of which of the following parasitic diseases (with its etiologic agent placed in parentheses) is usually UNACCOMPANIED by eosinophilia?

A) Ascariasis (Ascaris lumbricoides)
B) Hookworm (Ancylostoma duodenale or Necator americanus)
C) Liver fluke (Fasciola hepatica)
D) Pinworm (Enterobius vermicularis)
E) Trichinosis (Trichinella spiralis)

Answer: D 

(Year Posted: UI 141)

 

Key Code: P

When parasitic larvae invade the wrong host, e.g. dog hookworms or bird schistosomes in humans, the host inflammatory reactions tend to be:

A) absent
B) weaker than when the equivalent human-specific parasite invades humans
C) of about the same intensity as that seen for when the equivalent human-specific parasite invades humans
D) stronger that that seen when the equivalent human-specific parasite invades humans 

Answer: D 

(Year Posted: UI 142)

 

Key Code: I

Which of the following is NOT consistent with active SLE (systemic lupus erythematosis)?

A) Lower than normal levels of serum C3
B) Higher than normal levels of serum C4
C) Higher than normal levels of serum IgG
D) Presence of antibody that binds to double-stranded DNA (dsDNA) 

Answer: B 

(Year Posted: UI 143)

 

Key Code: I

The molecular target of the immune system in myasthenia gravis is:

A) desmoglein-3
B) the acetyl choline receptor
C) the insulin receptor
D) the platelet integrin gpIIG:IIIa 

Answer: B 

(Year Posted: UI 144)

 

Key Code: I

If a woman has myasthenia gravis and the disease is also seen in her newborn baby, what it the likely explanation?

A) Baby has generated an immune response which includes an autoimmune antibody
B) Maternal T lymphocytes have attacked the target for the autoimmune response within the baby
C) Maternal IgG has affected the target in the baby
D) The physostigmine treatment has caused side effects in the baby 
E) Antibodies in breast milk are causing the disease in the baby 

Answer: C 

(Year Posted: UI 145)

 

Key Code: M

Which one of the following would be an appropriate molecular clock for use when studying the phylogeny of BOTH bacteria and eukaryotes? Gene(s) encoding:

A) chitin synthetase
B) flagellin
C) peptidoglycan crosslinking enzymes
D) RNA-dependent RNA polymerase 
E) ribosomal RNA 

Answer: E 

(Year Posted: UI 146)

 

Key Code: B, Key Code: N

Hematogenous (blood-borne) spread of T. pallidum from a chance throughout the body is characteristic of which stage of the disease syphilis?

A) Primary
B) Secondary
C) Tertiary
D) Quaternary 

Answer: B 

(Year Posted: UI 147)

 

Key Code: P

Which of the following is correctly paired with its vector?

A) African trypanosomiasis,-louse
B) Ascaris,-reduviid bug
C) Chagas' disease,-tsetse fly
D) Malaria,-mosquito 
E) All of the above (A-D) are correctly paired

Answer: D 

(Year Posted: UI 148)

 

Key Code: P

Which of the following phenotypes is most strongly associated with enhanced resistance to falciparum malaria (malaria caused by Plasmodium falciparum)?

A) Blood group A
B) Blood group O
C) Duffy-positive blood group
D) Having both hemoglobin A and hemoglobin S 
E) Very dark skin color

Answer: D 

(Year Posted: UI 149)

 

Key Code: P

Which of the following can produce hematuria in infected persons and can be diagnosed by finding eggs with terminal spines in the urine of infected persons?

A) Crab louse
B) Deer tick
C) Pinworm
D) Schistosoma haematobium 
E) Trypanosoma cruzi

Answer: D 

(Year Posted:UI 150)

 

Key Code: M, Key Code: B

Which of the following survives the pasteurization process of milk?

A) Brucella abortus
B) Mycobacterium tuberculosis
C) Salmonella spp
D) Staphylococcus aureus 
E) None of the above (A-D)

Answer: E 

(Year Posted: UI 151)

 

Key Code: M, Key Code: B

Which of the following food preparation methods is effective at preventing botulism?

A) Canning green beans in water within glass jars brought to 100ºC for 30 minutes
B) Including nitrites during curing of meat
C) Keeping baked potatoes at room temperature wrapped in foil so that air cannot bring in bacteria
D) Smothering herbs with olive oil and storing in an airtight jar 
E) All of the above (A-D)

Answer: B 

(Year Posted: UI 152)

 

Key Code: M, Key Code: B

Which of the following is the best condition for using benzoic acid or sorbic acid in order to gain maximal antimicrobial activity?

A) At acidic pH as an ionized form
B) At acidic pH as an undissociated form
C) At alkaline pH as an ionized form
D) At alkaline pH as an undissociated form

Answer: B 

(Year Posted: UI 153)

 

Key Code: M, Key Code: B

Which is the best way to ensure all microbes are killed on surgical instruments?

A) Boiling at 100ºC for 30 minutes
B) Exposing instruments, wrapped in clear plastic bags, to u.v. light
C) Heating in an oven at 121ºC for 30 minutes
D) Heating in steam at 121ºC for 15 minutes

Answer: D 

(Year Posted: UI 154)

 

Key Code: M, Key Code: B

Which of the following acts as an antiseptic/disinfectant by oxidizing molecules in microbes?

A) Bleach or hypochlorite
B) Isopropyl alcohol and/or 70% ethanol
C) Phenol
D) Soap

Answer: A 

(Year Posted: UI 155)

 

Key Code: B

Which of the following is NOT a feature of Listeria monocytogenes (listeriosis)?

A) Gram positive
B) Growth at 4°C
C) Infection in pregnant women can cause miscarriage
D) Infects via oral route
E) Resistant to pasteurization

Answer: E 

(Year Posted:  UI 156)

 

Key Code: M, Key Code: B

Triclosan targets the same bacterial enzyme as does:

A) isoniazid
B) penicillin
C) rifampicin
D) sulfonamides
E) vancomycin

Answer: A 

(Year Posted:  UI 157)

 

Key Code: B

In order to detect the Shiga-like toxins (SLTs) produced by E.coli O157:H7, filtrates of fecal material can be tested against Vero cells in tissue culture. A control is to incubate the Vero cells with filtrate that has been premixed with antiserum against the SLTs. The results of such a test are given below for studies on a fecal specimen.

Test

Results

Vero cells plus filtratecytotoxicity

Vero cells plus antiserumno cytotoxicity

Vero cells plus filtrate plus antiserumcytotoxicity

Vero cell plus bufferno cytotoxicity

A) a problem with the materials (Vero cells, buffer, or antiserum) or a technical error
B) no evidence for SLT in filtrate
C) presence of SLT in antiserum
D) presence of SLT in filtrate

Answer: B 

(Year Posted: UI 158)

 

Key Code: B

Which of the following represents the main reservoir for Escherichia coli O157:H7?

A) Cattle
B) Fish from freshwater fish farms
C) Pigs
D) Poultry
E) Sheep

Answer: A 

(Year Posted: UI 159)

 

Key Code: M, Key Code: B

Which of the following is NOT killed by heating foods thoroughly so they reach the temperature of boiling water for at least 10 minutes? Therefore, the agent may still cause food poisoning if the cooked food is maintained at a slightly warm temperature.

A) Bacillus cereus
B) Campylobacter jejuni
C) Escherichia coli O157:H7
D) Mycobacterium tuberculosis
E) Staphylococcus aureus
F) Taenia saginata (tapeworm) in beef

Answer: A 

(Year Posted: UI 160)

 

Key Code: M, Key Code: B

The toxin formed by Clostridium botulinum:

A) is best produced in foods stored under acidic conditions, rather than at neutral pH
B) acts on peripheral nerve synapses
C) causes symptoms that mimic those seen with tetanus toxin
D) is found in significant levels in honey
E) its activity is blocked by antibody to the toxin produced by Clostridium tetani

Answer: B 

(Year Posted: UI 161)

 

Key Code: P, Key Code: M, Key Code: N

Which of the following conditions is (are) associated with development of paralysis?

A) After ingestion of shellfish containing toxic dinoflagellates producing saxitoxin
B) Development of Reye's syndrome after aspirin use and influenza
C) Ingestion of foods containing botulinum toxin
D) Occasionally following tick exposure and tick attachment
E) All of the above (A-D)

Answer: E 

(Year Posted: UI 162)

 

Key Code: B, Key Code: N

The specimen showing the highest likelihood of a positive result for bacteria in a person with typhoid fever is:

A) blood
B) bone marrow
C) feces
D) sputum
E) urine

Answer: B 

(Year Posted: UI 163)

 

Key Code: M, Key Code: B

Which of the following is the best way to kill microbes, including Clostridium, in dried blood?

A) Heating to 121ºC in a dry oven for 30 min
B) Heating to 121ºC in steam for 30 min
C) Spraying with bleach
D) All (A-C) are equivalent
E) None of the above (A-D) are effective

Answer: B 

(Year Posted: UI 164)

 

Key Code: B

What is the most common cause of meningitis among patients 18-50 years old?

A) Listeria monocytogenes
B) Neisseria meningitidis
C) Streptococcus pneumoniae
D) Haemophilus influenzae

Answer: C 

(Year Posted: UI 165)

 

Key Code: B, Key Code: I

To confirm the diagnosis of syphilis in a newborn baby, one needs to find:

A) IgG antibodies against Treponema pallidum in the baby
B) a positive culture of T. pallidum on blood agar
C) IgM antibodies against T. pallidum in the baby
D) rhinitis, rash and leukocytosis
E) evidence of child abuse

Answer: C 

(Year Posted: UI 166)

 

Key Code: B

Which of the following is consistent with syphilis acquired congenitally?

A) Mother is VDRL positive
B) Mother is RPR positive
C) Baby shows peeling of skin associated with a rash on the palms and sides
D) Spirochetes are visible in the placenta and umbilical cord tissues when they are stained by silver or visualized using dark field
E) All of the above (A-D)

Answer: E 

(Year Posted: UI 167)

 

Key Code: B

Lancet-shaped Gram positive diplococci in the blood of a 75-year-old with pneumonia probably represent:

A) Candida albicans
B) Enterococcus species
C) Haemophilus influenzae
D) Neisseria meningitidis
E) Streptococcus pneumoniae

Answer: E 

(Year Posted: UI 168)

 

  Key Code: I

A 19-year-old African-American presents to her primary care physician with an extranodal mass involving the mandible. Biopsy revealed lymphoma cells with the following characteristics: germline TCR genes, sIgM-positive, sIgD-positive, CD19-positive. What normal cell component markers are most similar to those expressed by the lymphoma cell?

A) Pre-B cell
B) Immature B cell
C) Mature B cell
D) Pre-T cell
E) Immature T cell

Answer: C 

(Year Posted: UI 169)

 

Key Code: B, Key Code: N

A nosocomial infection is defined as:

A) an infection of the inner chambers of the nose
B) being acquired in a hospital
C) being an infection that is described by a patient who has a morbid desire to be sick
D) an infection caused by a nosotoxin
E) an infection brought on by medical or surgical treatment

Answer: B 

(Year Posted: UI 170)

Key Code: B, Key Code: N

A child with a stiff neck, high white cell count in the CSF, and a blood culture showing Gram negative bacteria that grow on chocolate agar but NOT on blood agar is likely to have meningitis caused by:

A) Group B streptococci
B) Haemophilus influenzae
C) Pneumocystis carinii
D) Rickettsia rickettsii
E) Streptococcus pneumoniae 

Answer: B 

(Year Posted: UI 171)

 

Key Code: I

Which one of the following licensed vaccines is MOST LIKELY to elicit a T cell-dependent antibody response in a 13-month-old child?

A) Hepatitis B protein vaccine
B) Meningococcal polysaccharide vaccine group A
C) Meningococcal polysaccharide vaccine groups A, C, Y, and W-135 combined
D) Pneumococcal polyvalent vaccine 

Answer: A 

(Year Posted:UI 172)

 

Key Code: M, Key Code: B

The catalase test is used to distinguish between:

A) Escherichia and Pseudomonas
B) Escherichia and Streptococcus
C) Pseudomonas and Staphylococcus
D) Pseudomonas and Streptococcus
E) Staphylococcus and Streptococcus 

Answer: E 

(Year Posted:UI 173)

 

Key Code: M, Key Code: V

Which of the following procedures inactivate(s) prions?

A) Boiling in water
B) Filtering through air filters used for removing bacterial pathogens
C) X-irradiation doses suitable for inactivating parvovirus
D) All of the above (A-C)
E) None of the above (A-D) 

Answer: E 

(Year Posted:UI 174)

 

Key Code: M, Key Code: V, Key Code: N

In Britain, following the emergence of "mad cow disease," a variant form of Creutzfeldt-Jacob disease (CJD) was detected. This was considered a variant because, in contrast to the agent of conventional CJD, the etiologic agent of the variant CJD:

A) does not affect the brain
B) is characterized by the development of high antibody titers against the etiologic agent
C) is extremely common and, for a short period in the 1990's, was responsible for an annual death rate of 1 in 10,000 of the British adult human population
D) is not seen in people younger than 45 years old
E) produces a different pathological picture, when viewing microscope sections of the target organ 

Answer: E 

(Year Posted:UI 175)

 

Key Code: V, Key Code: N

You determine that your patient has elevated liver function tests and icteric sclera (yellowing of the whites of the eye). The patient works as a garbage collector and has recently traveled abroad. You should diagnose:

A) ethanol abuse
B) hepatitis
C) hepatitis A virus infection
D) hepatitis B virus infection
E) yellow fever 

Answer: B 

(Year Posted:UI 176)

 

Key Code: V

Which of the following vaccines protects against infection by hepatitis D virus?  A vaccine against:

A) Hepatitis A
B) Hepatitis B
C) Hepatitis C
D) HIV
E) None of the above (A-D) 

Answer: B 

(Year Posted: UI 177)

 

Key Code: V

To which of the following will a person develop antibody after immunization against hepatitis B virus?

A) HbcAg
B) HbeAg
C) HbsAg
D) All of the above (A-C)
E) None of the above (A-D) 

Answer: C 

(Year Posted:UI 178)

 

Key Code: I

In hemolytic disease of the newborn due to Rhesus incompatibility, the main way that red cells are destroyed is by:

A) complement-mediated lysis initiated via the alternative pathway
B) complement-mediated lysis initiated via the classical pathway
C) cytotoxic T cells
D) NK cells
E) opsonophagocytosis involving macrophages 

Answer: E 

(Year Posted:  UI 179)

 

Key Code: I

A woman has a miscarriage after 3 months of pregnancy. She states that she does not know who the father was but you are concerned that fetal red cells may sensitize her to Rhesus antigen. Although more than one answer may be possible, which combination of ABO and Rh blood groups carried by the woman carries the most risk for her sensitization against Rhesus antigen.  The woman is:

A) O Rh-
B) A Rh+
C) AB Rh-
D) AB Rh+
E) O Rh+ 

Answer: C 

(Year Posted:UI 180)

 

Key Code: I

The genes responsible for the antigenic epitopes of blood group antigens AB(O)H and I and i (cold agglutinin epitopes) directly encode:

A) carbohydrates
B) glycolipids
C) glycosyl transferases
D) lipases
E) peptidyl transferases 

Answer: C 

(Year Posted:UI 181)

 

Key Code: I

In order to prevent Rhesus hemolytic disease of the newborn developing in babies that are at risk because of the parents' blood group types, to whom and at what time should Rhogam (anti-Rhesus) be administered?

A) The baby should be transfused once with Rhogam in utero as soon as the procedure is feasible
B) The mother should receive it around the beginning of the third trimester and again within 3 days of birth
C) The mother should receive it before the first pregnancy and again as soon as she knows she is pregnant
D) The mother should receive it immediately after the baby is born and then again within about 2-3 weeks
E) The newborn baby should receive it within 24 hours of delivery 

Answer: B 

(Year Posted: UI 182)

 

Key Code: I

Autoimmune hemolytic anemia is generally caused by antibodies from two isotypes. These are IgG and:

A) IgA
B) IgC
C) IgD
D) IgE
E) IgM 

Answer: E 

(Year Posted:UI 183)

 

Key Code: I

The indirect Coombs' test  (indirect antiglobulin test) typically uses:

A) patient's red cells to see if IgG is bound to them
B) patient's red cells to see if immunoglobulin is bound to them
C) patient's serum to see if it forms a precipitate with donor plasma
D) patient's serum to see if it contains antibodies that bind to a variety of reagent red cells
E) patient's serum to see if it contains antibodies that bind to the patient's red cells 

Answer: D 

(Year Posted: UI 184)

 

Key Code: I

Which of the following products should usually be employed to transfuse an anemic immunocompromised patient?

A) Fresh frozen plasma
B) Irradiated leukocyte-reduced blood
C) Leukocyte-reduced blood
D) Whole blood 

Answer: B 

(Year Posted:UI 185)

 

Key Code: B

Tetracycline (doxycycline) is not used to treat gonorrhea in spite of its value for treating chlamydial   infections. Which of the following is a reason NOT to use doxycyline?

A) Doxycycline acts to induce gonococcal arthritis
B) Neisseria species are inherently not susceptible to doxycycline
C) The drug must be injected intramuscularly on 4 occasions during a 10-day treatment period
D) The infection will clear up naturally and then people no longer remain infected 
E) While most strains are susceptible, some are resistant

Answer: E  

(Year Posted:UI 186)

 

Key Code: I, Key Code: B

Examine the following table that shows skin test results obtained for an HIV-infected adult

Injected material

48-hour skin test result

30-minute skin test result

SalineNegativeNegative

HistamineNegative (faint)Positive

PPDNegativeNegative

Candida antigenNegativeNegative

Mumps antigenNegativeNegative

Tetanus toxoidNegativeNegative

Assuming there is nothing wrong with the antigens and reagents, these data show that the patient:

A) does not have TB
B) may have TB
C) has TB

Answer: B 

(Year Posted: UI 187)

 

Key Code: M, Key Code: B, Key Code: P

The acid fast stain can be employed to detect all of the following EXCEPT:

A) Cryptosporidium species
B) Mycobacterium species
C) Nocardia species
D) Staphylococcus species

Answer: D 

(Year Posted:  UI 188)

 

Key Code: B

Within the USA, which of the following describes most of those persons who are newly found to be PPD-positive but do NOT have active tuberculosis?  Most:

A) have been infected, but now have eliminated Mycobacterium tuberculosis
B) remain infected asymptomatically
C) have no risk of developing active tuberculosis
D) are highly contagious and so should be treated with antimycobacterial drugs
E) All of the above (A-D)

Answer: B 

(Year Posted: UI 189)

 

Key Code: F

What is the first-line drug therapy used for Pneumocystis carinii pneumonia?

A) amphotericin B
B) 5-fluorocytosine
C) fluconazole
D) foscarnet
E) trimethoprim-sulfamethoxazole

Answer: E 

(Year Posted:UI 190)

 

Key Code: F

What is the most reliable way of detecting Pneumocystis carinii as causing a pneumonia in AIDS?

A) Blood smear
B) Bronchoalveolar lavage
C) Culture on blood agar
D) Culture on Lowenstein-Jensen agar
E) Culture on Sabouraud agar

Answer: B 

(Year Posted:  UI 191)

 

Key Code: B

When comparing the number of bacteria/ml of blood from AIDS patients with Mycobacterium avium bacteremia with the number of bacteria/ml of blood from patients with sepsis caused by Gram-negative rods:

A) there are far more M. avium/ml
B) there are equivalent numbers of bacteria/ml in both types of patient
C) there are far less M. avium/ml

Answer: A 

(Year Posted: UI 192)

 

Key Code: B

Mycobacterium avium is found in all organs of the body but, in sections observed by histology, the largest numbers are found in:

A) cardiac muscle
B) central nervous
C) prostate
D) reticuloendothelial system (liver and bone marrow)

Answer: D 

(Year Posted: UI 193)

 

Key Code: B, Key Code: V, Key Code: P

For which of the following agents of sexually transmitted diseases is treatment with metronidazole routinely employed?

A) Chlamydia
B) Herpes simplex virus type II
C) Neisseria gonorrhoeae
D) Treponema pallidum
E) Trichomonas vaginalis

Answer: E 

(Year Posted: UI 194)

 

Key Code: B, Key Code: I

Approximately how long does it take after primary infection with Mycobacterium tuberculosis before a typical immunocompetent person will show a positive PPD test? (This is not referring to the length of time the skin test takes between injection of PPD and the development of the reaction)

A) 12 hours
B) 3 days
C) 1 week
D) 3-9 weeks
E) 4 months - 1 year

Answer: D 

(Year Posted:  UI 195)

 

Key Code: B

For a PPD test given to an immunocompetent person, what is INCORRECT?

A) a 15-mm induration is a positive reaction
B) the antigen is an attenuated Mycobacterium tuberculosis strain (Pasteur-derived D107)
C) the antigen is injected intradermally
D) the result should help determine whether a young person should receive INH prophylaxis
E) the test should be read 48-72 hours after injection

Answer: B 

(Year Posted: UI 196)

 

Key Code: M

How many 27-nm diameter viral particles, if placed in a line, would make up the length of a small Gram negative rod that is 2.7-um (micrometer) long?

A) 10
B) 100
C) 1,000
D) 10,000
E) 100,000
F) 1,000,000
G) 10,000,000
H) 10,000,000,000

Answer: B 

(Year Posted: UI 197)

 

Key Code: M

 

A Kirby Bauer assay is used to determine the susceptibility of a bacterium to antibiotics X, Y and Z to decide on treatment.  On the basis of the results shown, which is correct?

A) The patient should NOT be treated with X
B) The patient should be treated with Y and Z
C) The patient should be treated with Y or Z
D) The patient should be treated with X
E) Not enough data have been given to decide on treatment

Answer: E 

(Year Posted: UI 198)

 

Key Code: M

While working in the ER, a resident did a Gram stain of  a blood sample from a suspected case of bacterial meningitis. During the staining procedure he forgot to decolorize with alcohol prior to adding the safranin counterstain. If the meningitis is caused by Streptococcus pneumoniae the bacteria seen on the resident's slide will appear

A) red
B) purple
C) colorless
D) green
E) orange

Answer: B 

(Year Posted:UI 199)

 

Key Code: M

The major components of bacterial cells  can be separated  from one another by a variety of cell fractionation techniques. When this is done, the major parts of the electron transport system are found in

A) cell walls
B) outer membranes
C) nuclear remnants
D) cytoplasmic membranes
E) cytoplasm
F) peptidoglycan
G) capsules

Answer: D 

(Year Posted:UI 200)