Multiple Choice Questions 301-400

 

Key Code: I

Immunodeficiency disease can result from

A) a developmental defect of T lymphocytes
B) a developmental defect of bone marrow stem cells
C) a defect in phagocyte function
D) a defect in complement function
E) all of the above

Answer: E

(Year Posted:UI  301)

 

Key Code: I

The MHC contains the following except

A) genes that encode transplantation antigens
B) genes that encode immunoglobulins
C) genes that regulate immune responsiveness
D) genes that encode some components of complement
E) genes that encode class I and class II antigens

Answer: B

(Year Posted: UI  302)

 

Key Code: I

In clinical transplantation, cytotoxic antibodies reactive against antigens expressedon the grafted tissue

A) cause delayed rejection of the transplant
B) are responsible for hyperacute rejection
C) cause rejection when present in the donor
D) are not usually directed against HLA antigens
E) activate cytotoxic T cells which then cause hyperacute rejection

Answer: B

(Year Posted:UI  303)

 

Key Code: I

Rejection of a tumor may involve which of the following?

A) T cell-mediated cytotoxicity
B) ADCC
C) complement-dependent cytotoxicity
D) destruction of tumor cells by phagocytic cells
E) all are correct

Answer: E

(Year Posted:UI  304)

 

Key Code: I

Which of the following immunologic abnormalities is the consequence of the absence

A) increased ability to mount an antibody response to a T-dependent antigen
B) increased ability to reject tissue allografts
C) increased susceptibility to infection with fungi and M. tuberculosis
D) decreased susceptibility to infection by extracellular bacteria
E) none of the above

Answer: C

(Year Posted:UI  305)

 

Key Code: I

Injection into rabbits of a preparation of pooled human IgG could stimulate production of

A) anti-g heavy-chain antibody
B) anti-k chain antibody
C) anti-l chain antibody  
E) all are correct

Answer: E

(Year Posted:UI  306)

 

Key Code: I

The first immunoglobulin synthesized by the fetus is

A) IgA
B) IgE
C) IgG
D) IgM
E) none- the fetus does not synthesize immunoglobulins

Answer: D

(Year Posted:UI  307)

 

Key Code: I

SCID mice have a genetic defect that prevents development of functional

A) hematopoietic cells
B) B and T cells
C) T cells and NK cells
D) pluripotential stem cells
E) myeloid cells

Answer: B

(Year Posted:UI  308)

 

Key Code: I

The administration of vaccines is not without hazard. Of the following, which is least likely to adversely affect an immunocompromised host?

A) measles vaccine
B) pneumococcal vaccine
C) bacille Calmette-Guérin
D) mumps vaccine
E) Sabin poliomyelitis vaccine

Answer: B

(Year Posted:UI  309)

 

Key Code: I

Patients with DiGeorge syndrome may fail to produce IgG in response to immunization with T-dependent antigens because

A) they have a decreased number of B cells, which produce IgG
B) they have increased numbers of suppressor T cells
C) they have a decreased number of helper T cells
D) they have abnormal antigen-presenting cells
E) they cannot produce IgM during primary responses

Answer: C

(Year Posted:UI  310)

 

Key Code: I

Match the following statements/items with the choices below (choices may be used more than once)

A) CD4 and CD8 (CD4+, CD8+)
B) CD3
C) high affinity IL-2 receptor
D) MHC class I antigens
E) MHC class II antigens

__B__    signal transducing molecule on all T cells

__D_     on all nucleated cells

__C_     induced on activated T cells

__E_     interact with CD4

__A_     on the majority of thymic T cells

(Year Posted:UI  311)

 

Key Code: I

Use the following options to answer questions

A) Myasthenia Gravis
B) Multiple Sclerosis
C) Systemic Lupus Erythematosus
D) Rheumatoid Arthritis
E) Insulin Dependent Diabetes Mellitus
F) Hashimoto's Thyroiditis
G) Graves Disease

__D__    Lydia Lopez went to the clinic complaining of fatigue and joint pains. Laboratory tests performed on synovial fluid extracted from her elbow revealed the presence of numerous inflammatory cells including TH1 CD4 cells, macrophages and neutrophils. In addition, immune complexes consisting of antibody specific for the Fc fragment of IgG were found. The likely diagnosis is

__G_     This disease is purely antibody mediated and results from the binding of a "stimulating" autoantibody to a receptor

__F_     This disease is characterized by a TDTH  response to thyroid antigens

__A_     Curtis Jones, a retired sanitation worker developed double vision. Upon neurological examination he was observed to have weakness of his facial muscles and his tongue and abnormality in ocular movements. He refused further testing and treatment. Several months later he developed difficulty in chewing, swallowing food and even breathing. He again visited a neurologist. He was found to have elevated serum titers of autoantibodies. The likely diagnosis is

(Year Posted: UI  312)

 

Key Code: I

The following options can be used for questions

A) theophyline
B) cromolyn sodium
C) corticosteroids
D) antihistamine
E) epinephrine
F) azathioprine

__B__    Prevents degranulation by blocking Ca2+ influx into cell

__A_     Prevents degranulation by maintaining high level of cAMP

__E_     Rapidly relaxes smooth muscle constriction

__C_     Blocks cytokine and leukotriene production and reduces inflammation

(Year Posted: UI  313)

 

Key Code: I

The following case is to be used in answering questions

Christopher Glewin was the only child born to his parents. His growth and development were normal. When he was 12 years old he began to lose weight and developed enormous thirst such that he was consuming over 3 liters of liquid a day. The thirst and excess fluid consumption was accompanied by frequent urination. He was taken to the family doctor, who diagnosed diabetes mellitus. It turned out that several relatives of Christopher’s father had also developed juvenile onset diabetes. Christopher was started on daily insulin injections but his blood sugar was always difficult to control.

When he was 35 years old, during a routine annual physical examination, his physician found that his blood pressure was elevated and that his urine tested positive for the presence of protein. A serum creatinine test was obtained and found to be 7.5 mg dl- (normal <1.0 mg dl-). On the basis of these results, Christopher’s physician suspected that he had developed renal complications of diabetes. A Kidney biopsy was performed and revealed extensive diabetic glomerulosclerosis, showing that Christopher was in imminent danger  of kidney failure. He was therefore scheduled for hemodialysis twice a week. He was also put on a waiting list for a cadaveric kidney transplant. Within three months, a cadaveric kidney was found from a 20-year-old man who was fatally injured in a motorcycle accident.

Christopher was admitted to the hospital, his serum was tested and found to be negative for antibody to some of the donor HLA-A & HLA-B antigens. On the following morning, his own kidneys were removed by a surgeon and replaced with the donor a kidney. During the procedure Christopher was given 100 mg methylprednisolone and 40 mg of anti-ICAM monoclonal antibody. During the first day after his operation the transplanted kidney put out 200 ml of urine. This is only about one-fifth the normal output for a healthy person but usual for a newly transplanted kidney and showed that the organ was functioning.

Following surgery, Christopher was given 450 mg cyclosporin, 100 mg azathioprine, 160 mg methylprednisolone and 40 mg of anti-ICAM antibodies. The serum creatinine returned to normal during the next 5 days. After the fifth day anti-ICAM antibodies were stopped and Christopher was continued on 100 mg azathioprine, 400 mg cyclosporin and 20 mg prednisone. Christopher was discharged from the hospital 10 days after the transplant was performed.

One week after discharge from the hospital Christopher noticed that his urine output had fallen to about half normal. A renal biopsy revealed the presence of many lymphocytes in the transplant indicating that the kidney was undergoing  rejection.

His immunosuppressive therapy was increased to 500 mg methylprednisolone intravenously, the cyclosporin was continued, and iv injections of 5 mg of a monoclonal antibody to CD3 were given for 10 days. This immunosuppresive regimen successfully suppressed the symptoms and Christopher continued to do well.

Within a year of the transplant Christopher returned to his civil engineering job. His blood pressure remains normal. His serum creatinine is <1.0 mg dl-l and he continues to take low doses of azathioprine, prednisone and cyclosporin.

The target autoantigen in juvenile diabetes is found on

A) Pancreatic duct cells
B) Beta cells of pancreas
C) Alpha cells of pancreas
D) Delta cells of pancreas
E) Acinar tissue

Answer: B

Which immunosuppresive agent would be expected to affect direct cell-cell interactions which occur between leukocytes and endothelial cells

A) Anti-CD4
B) Cyclosporin A
C) Azatrhioprine
D) a and b only
E) Anti-ICAM antibody

Answer: E

Graft rejection in this patient may be defined as

A) Graft-versus-host disease
B) Hyperacute rejection
C) Acute rejection
D) Vascular rejection
E) ADCC

Answer: C

A sandwich ELISA was used to determine whether autoantibody to pancreas antigens were present in Christopher’s serum. Which set-up would allow for the measurement of such antibodies?

 Coating agentMiddle layer agentPeroxidase-labeled developing agent

Amouse anti-human-Igpatient’s serummonoclonal mouse anti-human Ig

Bmouse anti-human-Igpatient’s serummouse anti-pancreas Ag

Cpancreas Agmonoclonal mouse anti-human Igpatient’s serum

Dpancreas Agpatient’s serummonoclonal mouse anti-human Ig

Epatient’s serumpancreas Agmonoclonal mouse anti-human Ig


Answer: D

Treatment of this patient with mouse anti-CD3 antibody

A) will lower the number of T cells in the peripheral blood and tissue
B) will activate the alternate pathway of complement
C) will predispose Christopher to opportunistic infections
D) will stop the generation of precursor T cells in bone marrow
E) A and C

Answer: E

Which of the following factors can confer susceptibility to juvenile onset diabetes?

A) viral or bacterial infections
B) HLA class II (DR3, DR4)
C) a and b
D) HLA class I B27 allele
E) elevated levels of testosterone

Answer: C

The graft (transplant) that Christopher received was

A) an autograft
B) an allograft
C) a xenograft
D) syngeneic with respect to his own major and minor histcompatibility loci
E) infected with a virus

Answer: B

In Insulin-Dependent Diabetes Mellitus, b islet cells are primarily destroyed byIn Insulin-Dependent Diabetes Mellitus, b islet cells are primarily destroyed by

A) cytotoxic T lymphocytes
B) activated macrophages
C) anti-insulim antibodies and complement
D) mast cell degranulation
E) natural killer cells

Answer: A

(Year Posted:UI  314)

 

Key Code: I

Choose the answers for questions from the list below

A) 56lckF) CD28

B) p59fynG) CD40L

C) NF-ATH) B7

D) CD45I)  CD8

E) IgGJ) calcinerium

__D__   this T cell membrane protein has cytosolic domains with phosphatase activity

__H_    dendritic cells constitutively express this molecule which interacts with CD28

__J_     the phosphatase involved in generating active form of the transcription factor NF-AT

__G_    mutation or deletion of this molecule results in hyper-IgM syndrome

__I_     knockout mice lacking I MHC class molecules fail to produce thymocytes bearing this molecule

(Year Posted:UI  315)

 

Key Code: I

Questions below refer to the following immunoassay and results

The concentration of serum IgG was measured by ELISA from three patients whose sera was sent to the laboratory for testing. Briefly an ELISA plate was coated with antibody to human IgG. The plate was blocked and then incubated with various dilutions of patient's sera. The plate was then washed and incubated with goat anti-human IgG conjugated to alkaline phosphatase followed by the addition of substrate. Color development was measured on an ELISA reader at an optical density of 405 nm. A standard curve was obtained using known concentrations of a human IgG antibody.

 

The following ELISA results were obtained for three patients. Use the standard curve and the OD 405 nm values to determine the concentration of IgG in the undiluted samples of each patient’s serum. Normal serum concentration of IgG is 2.5-10 mg/ml.

OD 405 nm

Patient 12.630 (1 to 50,000 dilution)

Patient 20.136 (1 to 10,000 dilution)

Patient 30.731 (1 to 10,000 dilution)

Which of the above patients has an IgG immunodeficiency and approximately how many mg/ml of IgG does he have in his sera

A) patient 1  >100 mg/m
B) patient 1     20 mg/m
C) patient 2  < 0.5 mg/m
D) patient 2  > 2.0 mg/ml
E) patient 3  < 5.0 mg/ml

Answer: C

Patient 2 was found to have slightly higher than normal serum levels of IgM antibody. This patient likely suffers from which of the following

A) Hyper IgM syndrome
B) SCID immunodeficiency
C) Bruton’s agammaglobulinemia
D) Wiskott Aldrich syndrome

Answer: A

Patient 3 has low IgM and  is unable to respond to polysaccharide antigens. Which of the following immunodeficiency diseases is most consistent with this?

A) Hyper IgM syndrome
B) Bruton’s agammaglobulinemia
C) Wiskott Aldrich syndrome
D) Bare lymphocyte syndrome
E) Chediak Higashi syndrome

Answer: C

Based on his IgG concentration, patient 1 should undergo further tests for a possible diagnosis of

A) SCID immunodeficiency
B) B cell lymphoma
C) Hereditary angioneurotic edema
D) Bruton’s agammaglobulinemias

Answer: B

(Year Posted:UI  316)

 

Key Code: B

 

Key Code: B

A patient diagnosed with cholera would be expected to

A) have a high fever
B) be infected with a invasive pathogen
C) have an increased enterocyte cAMP concentration resulting from a bacterial encoded adenylate cyclase
D) have an increased enterocyte cAMP resulting from a stimulation of the host's own adenylate cyclase
E) have bloody diarrhea

Answer: D

(Year Posted: UI  318)

 

Key Code: B

All of the following characteristics of Vibrio parahaemolyticus are true, EXCEPT

A) causes bloody diarrhea after ingestion of contaminated shellfish
B) it is a curved gram-negative rod
C) its pathogenic mechanism is unclear
D) can be isolated from stool
E) requires aggressive treatment with antibiotics

Answer: E

(Year Posted:UI  319)

 

Key Code: B

The best therapy for severe cases of cholera is

A) antimicrobial therapy
B) vaccination
C) replacement of electrolytes
D) outpatient treatment
E) antimotility therapy

Answer: C

(Year Posted:UI  320)

 

Key Code: B

The following statements about Vibrio cholerae O1 are true EXCEPT that

A) invades the small intestine
B) is often associated with marine environments
C) causes disease through the production of an enterotoxin
D) reacts with group 1 antiserum against (O) antigens
E) it is associated with epidemics

Answer: A

(Year Posted:UI  321)

 

Key Code: B

The O1 in Vibrio cholerae O1 strain designation refers to

A) the organism's capsule
B) the organism's LPS-O antigen
C) the organism's flagella
D) the organism's major outer membrane lipoprotein
E) the fact that this was the first Vibrio cholerae strain isolated

Answer: B

(Year Posted:UI  322)

Key Code: B

Endotoxin

A) is produced by Gram-positive bacteria
B) has profound biological effects due to the Lipid A moiety
C) has important enzymatic activities
D) is composed of protein
E) is usually found in secreted rather than cell-associated form

Answer: B

(Year Posted:UI  326)

 

Key Code: B

Enterotoxins

A) are not secreted by the bacterial cell
B) are not produced by Escherichia coli
C) stimulate adenyl cyclase or guanylate cyclase
D) are responsible for endotoxic shock
E) contain lipid A

Answer: C

(Year Posted:UI  327)

 

Key Code: B

Which laboratory characteristic does not belong to the Family Enterobacteriaceae

A) glucose fermentation
B) positive motility
C) gram negative bacilli
D) positive cytochrome oxidase
E) reduction of nitrates to nitrites

Answer: D

(Year Posted:UI  328)

 

Key Code: B

The most common etiologic agent of travelers' diarrhea

A) Shigella sonnei
B) Enterohemorrhagic E. coli
C) Salmonella species
D) Enterotoxigenic E. coli
E) Staphylococcus aureus

Answer: D

(Year Posted: UI  329)

 

Key Code: B

Enterotoxigenic E. coli (ETEC)

A) is the major cause of travelers' diarrhea
B) is the leading cause of urinary tract infections
C) is an important cause of neonatal meningitis
D) causes pulmonary infections
E) is able to invade the enterocytes and bloodstream

Answer: A

(Year Posted:UI  330)

 

Key Code: B

Which one of the following is not an invasive organism?

A) Shigella sonnei
B) Salmonella spp.
C) Enterotoxigenic Escherichia coli
D) Campylobacter jejuni
E) Shigella flexneri

Answer: C

(Year Posted:UI  331)

 

Key Code: B

Which of the following is not true about Shigella?

A) The genus includes animal and human pathogens
B) Causes bacillary dysentery
C) Most strains are lactose nonfermenters
D) It is non-motile
E) It is associated with hemolytic uremic syndrome

Answer: A

(Year Posted: UI  332)

 

Key Code: B

Select the best treatment for mild cases of shigellosis in adults

A) Ampicillin
B) Penicillin
C) Bactrim
D) Nalidixic acid
E) None

Answer: E

(Year Posted: UI  333)

 

Key Code: B

Humans acquire shigellosis from

A) dogs
B) cats
C) swine
D) chikens
E) humans

Answer: E

(Year Posted:UI  334)

 

Key Code: B

Assume that a nonmotile, gram-negative rod is isolated from the bloody stool of a

A) typhoid fever
B) cholera
C) staphylococcal food poisoning
D) shigellosis
E) amebiasis

Answer: D

(Year Posted:UI  335)

 

Key Code: B

Which of the following organisms has the lowest infective dose?

A) Enterotoxigenic Escherichia coli
B) Enteroinvasive E. coli
C) Salmonella enteriditis
D) Shigella flexneri
E) Vibrio cholerae

Answer: D

(Year Posted: UI  336)

 

Key Code: B

Which of the following properties distinguishes Salmonella from Shigella?

A) Gram-stain reaction
B) motility
C) presence of a capsule
D) morphology
E) fermentation of lactose

Answer: B

(Year Posted:UI  337)

 

Key Code: B

The most common agent of gastroenteritis in the U.S. is

A) Salmonella typhi
B) Campylobacter jejuni
C) Shigella soneii
D) ETEC
E) EHEC

Answer: B

(Year Posted:UI  338)

 

Key Code: B

Campylobacter jejuni gastroenteritis is associated with consumption of contaminated

A) milk
B) chiken
C) clams
D) hamburgers

Answer: C

(Year Posted:UI  339)

 

Key Code: B

Campylobacter jejuni

A) is biochemically very active
B) is found only in the human gastrointestinal tract
C) is one of the most common causes of infectious diarrhea
D) does not cause bloody diarrheic stools
E) is a Gram-positive sporulated rod

Answer: C

(Year Posted:UI  340)

 

Key Code: B

The average case of gastroenteritis of Salmonella origin is characterized by

A) a short incubation, diarrhea, and abdominal pain
B) a prolonged course with septicemia
C) a long incubation period with diarrhea, but no fever
D) a disease resembling typhoid fever
E) a true intoxication

Answer: A

(Year Posted:UI  341)

 

Key Code: B

All of the following statements refer to typhoid fever EXCEPT

A) humans are the only known hosts
B) bacteremia occurs during the first week of the disease
C) rose spots may appear on the skin of the abdomen during the second week of the disease
D) more that 50% of the patients become chronic carriers
E) the organism can be isolated from blood, stool, and urine

Answer: D

(Year Posted:UI  342)

 

Key Code: B

Which organism is most likely to be isolated from a septicemic patient?

A) Enteroaggregative E. coli
B) Shigella flexnerii
C) Enteroinvasive E. coli
D) Salmonella enteriditis
E) Shigella sonnei

Answer: D

(Year Posted:UI  343)

 

Key Code: B

Salmonella enteriditis is part of the normal flora of

A) dogs
B) cats
C) chikens
D) pigs
E) human

Answer: C

(Year Posted:UI  344)

 

Key Code: B

The best specimen for the diagnosis of typhoid fever in the first week of illness is

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

Answer: B

(Year Posted:UI  345)

 

Key Code: B

In the laboratory diagnosis of enteric pathogens, to discriminate Salmonella and Shigella

A) ferment glucose
B) ferment lactose
C) produce cytochrome oxidase
D) reduce nitrates
E) grow on MacConkey agar

Answer: B

(Year Posted:UI  346)

 

Key Code: B

The reservoir of Salmonella typhi is

A) dogs
B) cats
C) turtles
D) pigs
E) humans

Answer: E

(Year Posted:UI  347)

 

Key Code: B

The following are sources of human Salmonella infection

A) poultry products
B) turtles
C) sewage-contaminated food and water
D) iguanas
E) all of the above

Answer: E

(Year Posted:UI  348)

 

Key Code: B

Assume that a diarrheal disease was transmitted by infected raw eggs. Which of the

A) Salmonella sp
B) Vibrio cholerae
C) Staphylococcus aureus
D) Shigella sonnei
E) Campylobacter jejuni

Answer: A

(Year Posted:UI  349)

 

Key Code: B

A toxin of Escherichia coli that is very similar to the Shiga-toxin of Shigella dysenteriae

A) heat-labile LT enterotoxin
B) heat-stable ST enterotoxin
C) adherence-promoting toxin
D) verotoxin
E) exfoliative toxin

Answer: D

(Year Posted:UI  350)

Key Code: B

Hemolytic uremic syndrome (HUS) is a sequelae associated with

A) EHEC (Enterohemorrhagic E. coli)
B) EIEC (Enteroinvasive E. coli)
C) ETEC (Enterotoxigenic E. coli)
D) EPEC (Enteropathogenic E. coli)
E) EAggEC (Enteroaggregative E coli)

Answer: A

(Year Posted:UI  351)

 

Key Code: B

Which of the following is most correctly described as a facultative intracellular enteric

A) EHEC (Enterohemorrhagic E. coli
B) EIEC (Enteroinvasive E. coli)
C) ETEC (Enterotoxigenic E. coli)
D) EPEC (Enteropathogenic E. coli)

Answer: B

(Year Posted:UI  352)

 

Key Code: B

Which Escherichia coli causes a dysentery that resembles Shigella?

A) Enterohemorrhagic E. coli, EHEC
B) Enteropathogenic E. coli, EPEC
C) Enteroaggregative E. coli, EAggEC
D) Enterotoxigenic E. coli, ETEC
E) Enteroinvasive E. coli, EIEC

Answer: E

(Year Posted:UI  353)

 

Key Code: B

Infection with this microorganism, mimics acute appendicitis:

A) Yersinia enterocolitica
B) Campylobacter jejun
C) Vibrio parahemolyticus
D) ETEC
E) Vibrio cholerae

Answer: A

(Year Posted:UI  354)

 

Key Code: B

The pathogenic mechanisms that make Helicobacter pylori the causative agent of gastritis

A) urease production
B) invasive abilities
C) motility
D) microaeophilism
E) mucinase

Answer: B

(Year Posted:UI  355)

 

Key Code: B

Campylobacter and Helicobacter share the following characteristics EXCEPT ONE

A) small size
B) single polar flagellum
C) microaerophillic nature
D) found exclusively in humans
E) curved Gram-negative rods

Answer: D

(Year Posted:UI  356)

 

Key Code: B

Almost all persons infected with Helicobacter pylori will

A) eventually develop peptic ulcers
B) develop severe diarrhea
C) develop bacteremia+
D) have a type A personality

Answer: A

(Year Posted:UI  357)

 

Key Code: B

A patient has been diagnosed with a gastric ulcer and his serum shows reactivity with Helicobacter pylori antigens. Which of the following is true?

A) Helicobacter pylori infection most likely has nothing to do with the patient's condition
B) The patient will be treated with amoxicillin to eradicate H. pylori colonization and eliminate its recurrence
C) The patient's gastrin-hydrochloric homeostasis has been maintained
D) Damage to the patient's gastric mucosa has been primarily caused by the patient's own immune response

Answer: D

(Year Posted:UI  358)

 

Key Code: B

Of the following known causes of diarrhea, which one is most likely to be associated with

A) Clostridium perfringens
B) Clostridium difficile
C) Shigella sonnei
D) Campylobacter jejuni
E) Clostridium botulinum

Answer: B

(Year Posted:UI  359)

 

Key Code: B

All of the following statements regarding Clostridium difficile enterocolitis are true EXCEPT

A) It is associated with recent use of antibiotics
B) The preferred treatment is IV vancomycin
C) Relapse may occur after appropriate treatment
D) Detection of the toxin in stool is the best means of diagnosis
E) It can affect hospitalized patients

Answer: B

(Year Posted:UI  360)

 

Key Code: B

The main difference between food-poisoning and food-related illness (such as salmonellosis) is

A) food source
B) presence or absence of fever
C) incubation time
D) presence or absence of nausea

Answer: A

(Year Posted:UI  361)

 

Key Code: B

Gastrointestinal disease due to Bacillus cereus

A) may manifest as a type of food poisoning resembling botulism
B) may manifest after 2 hours of consuming contaminated food
C) is preventable by immunization
D) is dependent upon the ability of B. cereus to produce an antiphagocytic capsule
E) is dependent upon the ability of B. cereus to produce a neurotoxin

Answer: B

(Year Posted:UI  362)

 

Key Code: B

Food poisoning caused by S. aureus is due to a production of

A) hemolysin
B) lethal toxin
C) enterotoxin A
D) leukocidin
E) endotoxin

Answer: C

(Year Posted:UI  363)

 

Key Code: B

The enterotoxin elaborated by certain strains of S. aureus

A) causes acute gastrointestinal symptoms within 10 to 12 hours of ingestion
B) is composed of high molecular weight proteins
C) appears to have an effect on the central nervous system
D) is lethal to PMNs by disrupting their membranes
E) is susceptible to gastric acid

Answer: C

(Year Posted:UI  364)

 

Key Code: B

In botulism, the patient develops dizziness, blurred vision with fixed dilated pupils and weakness due to

A) anti-cholinergic effects of the toxin
B) invasive properties of the bacillus
C) stimulation of cAMP
D) stimulation of cGMP
E) invasive properties of the spores

Answer: A

(Year Posted: UI  365)

 

Key Code: B

All of the following microorganisms should be considered in the differential diagnosis of bloody diarrhea in a 30-year-old patient EXCEPT ONE

A) Salmonella
B) Shigella
C) Campylobacter
D) Yersinia
E) Enterotoxigenic E. coli

Answer: E

(Year Posted:UI  366)

 

Key Code: B

Which of the following causes of food poisoning or food-related illness does not involve an

A) Staphylococcus aureus
B) Salmonella enteritidis
C) Vibrio cholerae
D) Clostridium perfringens
E) Bacillus cereus

Answer: B

(Year Posted: UI  367)

 

Key Code: B

The infection with the following microorganism is most likely to result in septicemia

A) EIEC
B) Shigella flexnerii
C) Salmonella enteriditis
D) EAggEC
E) ETEC

Answer: C

(Year Posted:UI  368)

 

Key Code: B

All of the following pathogenic microorganisms can easily be isolated in blood cultures EXCEPT

A) Salmonella typhi
B) Streptococcus pneumoniae
C) Mycobacterium tuberculosis
D) Staphylococcus aureus
E) Staphylococcus epidermidis

Answer: C

(Year Posted:UI  369)

 

Key Code: B

The following microorganism causes food poisoning by the production of an exotoxin in vivo

A) Staphylococcus aureus
B) Salmonella typhi
C) Clostridium botulinum
D) Shigella boydii
E) Clostridium perfringens

Answer: E

(Year Posted:UI  370)

 

Key Code: B

All of the following statements about Listeria monocytogenes are true EXCEPT that

A) it primarily causes a disease among animals and occasionally is passed to humans
B) meningitis is the most commonly recognized form of listeriosis
C) the bacterium can only be cultured in human cells
D) neonatal listeriosis occurs as a result of genital tract infection of the mother
E) infection causes an increase of circulating monocytes

Answer: C

(Year Posted:UI  371)

 

Key Code: B

All of the following are true of Listeria monocytogenes EXCEPT that

A) intracellular survival requires synthesis of listeriolysin O
B) it can be isolated from blood cultures and spinal fluid of infected babies
C) produces a potent enterotoxin
D) it is a gram-positive rod
E) it can cause food-borne disease

Answer: C

(Year Posted:UI  372)

 

Key Code: B

Select the causative agent of Lyme disease

A) Borrelia burgdorferii
B) Listeria monocytogenes
C) Borrelia hermsi
D) Leptospira interrogans
E) Pasteurella multocida

Answer: A

(Year Posted:UI  373)

 

Key Code: B

The treatment of choice for bubonic or pneumonic plague

A) Amoxicillin
B) Streptomycin
C) Cephalosporins
D) Trimetoprim
E) There is no treatment for plague

Answer: B

(Year Posted:UI  374)

 

Key Code: B

A short encapsulated Gram-negative rod associated with infections caused by dog or cat bites

A) Borrelia burgdorferii
B) Brucella suis
C) Borrelia hermsi
D) Leptospira interrogans
E) Pasteurella multocida

Answer: E

(Year Posted: UI  375)

Key Code: B

All of the following statements about spirochetes are true EXCEPT that

A) Endemic relapsing fever is caused by mosquito bites from infected rodents
B) Lyme disease is caused by tick bites from infected deer
C) B. recurrentis causes a cyclic disease with relapses due to its antigenic variations
D) In relapsing fever, routine blood smears can reveal infecting spirochetes

Answer: A

(Year Posted:UI  376)

 

Key Code: B

For each of the clinical cases discussed below, select the microorganism most likely to have caused the illness described

A) A 28-year old farmer was in good health until the preceding day was admitted to the hospital form the ER. He felt feverish, had chills, nausea and vomiting. His rectal examination revealed occult blood in his stool. A stool exam for fecal leukocytes was positive and the stool culture was diagnostic. The microbe was a non-lactose fermenter on MacConkey agar, H2S negative,and non-motile at both, 250C and 370C

B) A 29-year old complained of fatigue, stiff neck, flu-like symptoms and headache. He is an avid fisherman and hunter. Upon questioning he did not remember being bitten by ticks, although he recalled seeing an expanding red circle with a center like a bull's eye on his right arm that eventually disappeared. He taught it was some kind of an insect bite

C) A 6-month old baby develops weakness and flaccid paralysis in his extremities 2 days after his mother mixed his formula with honey

D) A group of medical students felt sick with nausea, vomiting, and abdominal cramping a few hours after eating sandwiches and potato salad at a local restaurant. They had no diarrhea

Answers:

Yersinia enterocoliticaBorrelia burgdorferii  B

Salmonella typhiShigella soneii   A

Listeria monocytogenesBacillus cereus

Clostridium botulinum  CStaphylococcus aureus  D

Clostridium perfringensShigella boydi


(Year Posted: 2001 UI  377)

 

Key Code: B

Which of the following microorganisms is most likely to produce food poisoning within 3 hours of ingestion?

A) Clostridium perfringens
B) Clostridium botulinum
C) Bacillus cereus
D) Enterotoxigenic E. coli
E) Enterococcus faecalis

Answer: B

(Year Posted: 2001 UI  378)

 

Key Code: B

Your patient is a 30-year old female who just returned from South America. The day before leaving, several members of her group developed fever, abdominal cramps and bloody diarrhea. Of the following, which is the least likely cause of this infection?

A) EHEC (Enterohemorrhagic E. coli)
B) ETEC (Enterotoxigenic E. coli)
C) Salmonella typhi
D) Shigella sonei
E) EIEC (Enteroinvasive E. coli)

Answer: B

(Year Posted: 2001 UI  379)

 

Key Code: B

A unique feature of gastroenteritis caused by Yersinia enterocolitica

A) nausea
B) vomiting
C) mimics appendicitis
D) abdominal discomfort
E) bacteremia

Answer: C

(Year Posted: 2001 UI  380)

 

Key Code: B

A 10-year old girl who received a deep laceration when she was water skiing was just brought into your office.  Her parents state that she has had no previous immunization against tetanus.  As protection against the possibility of tetanus now and in the future, the preferred method of treatment would be

A) a mixture of tetanus toxoid and tetanus immune globulin (human) as one injection
B) a tetanus toxoid injection this visit, with an injection of tetanus immune globulin (human) approximately three weeks later
C) separate injections of tetanus toxoid and tetanus immune globulin (human) in different sites on this one visit
D) a tetanus immune globulin (human) injection this visit, with an injection of tetanus toxoid about three weeks later
E) a tetanus immune  globulin (human) injection this visit, with an injection of tetanus toxoid about five weeks later

Answer: C

(Year Posted: 2001 UI  381)

 

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: 2001 UI  382)

 

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 rickettsi
E) Yersinia pestis

Answer: D

(Year Posted: 2001 UI  383)

 

Key Code: B

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: 2001 UI  384)

 

Key Code: B

An orally administered bacterium causes paralysis in mice. What observation provides DIRECT EVIDENCE that a toxin is required for this effect?

A) Anti-toxin antibody administered to mice before infection abrogates paralysis
B) Mice that recover from the disease are immune to the effects of a subsequent infection
C) Mice that recover from the disease make antibodies to the toxin
D) Purified toxin lyses mouse neuronal cells in vitro
E) The deduced amino acid sequence of the toxin is 30% homologous with that of botulinum toxin

Answer: A

(Year Posted: 2001 UI  385)

 

Key Code: B

A 65-year-old male develops endocarditis following urinary catheterization. Gram-positive, catalase-negative cocci are isolated from a blood culture. The MOST LIKELY agent is

A) Streptococcus viridans
B) Staphylococcus epidermidis
C) Streptococcus pyogenes (group A streptococci)
D) Enterococcus faecalis
E) Staphylococcus aureus
F) Staphylococcus saprophyticus
G) Streptococcus pneumoniae

Answer: D

(Year Posted: 2001 UI  386)

 

Key Code: B

A 13-year old boy develops marked swelling in his right inguinal lymph node accompanied by a fever of 104oF. He and his family have just returned from a vacation trip to the Four Corners region of Arizona, New Mexico, Colorado and Utah. An aspirate from the painful, swollen node reveals Gram-negative rods. A direct immunofluorescent assay on the same aspirate provides a definitive diagnosis. The child is treated with streptomycin, and the aspirate is sent for culture. The culture yields white colonies on MacConkey agar grown at room temperature. The MOST LIKELY agent is

A) Brucella abortus
B) Enterohemorrhagic Escherichia coli
C) Franciscella tularensis
D) Yersinia pestis
E) Campylobacter jejuni

Answer: D

(Year Posted: 2001 UI  387)

 

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 mirabilis
C) Legionella pneumophila
D) Moraxella catarrhalis
E) Bacteroides fragilis
F) Peptostreptococcus micros
G) Prevotella melaninogenica

Answer: E

(Year Posted: 2001 UI  388)

 

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 genes
B) pili
C) capsule
D) endotoxin
E) hyaluronidase

Answer: B

(Year Posted: 2001 UI  389)

 

Key Code: B

Refer to the case description below to answer questions

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

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

 

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

 

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  390)

 

Key Code: B

Salmonella enterocolitica typically produces which one of the following reactions on a Kligler iron agar slant (slant / butt)?

A) acid / acid, gas / H2S
B) acid / acid, no gas / no H2S
C) alkaline / acid, gas / H2S
D) alkaline / acid, gas / no H2S
E) no change / no change

Answer: C

(Year Posted:UI  391)

 

Key Code: B

A 20 year old female is diagnosed with gonorrhea. Tetracycline therapy is prescribed along with an antibiotic affective against Neisseria gonorrhoeae. Which of the following is the BEST explanation for the use of tetracycline?

A) to take advantage of synergism
B) to treat undiagnosed Chlamydia infection
C) for prevention of further infection
D) for blocking N. gonorrhoeae antigenic switching
E) to prevent penicillin allergy

Answer: B

(Year Posted:UI  392)

 

Key Code: B

A urine culture from a catheterized patient in a nursing home yields a Gram-negative rod that ferments glucose, produces H2S and is able to produce CO2 and NH3 from urea. Which of the following is also likely to be a characteristic of this organism?

A) ferments lactose
B) forms endospores
C) produces neutral endproducts of glucose fermentation
D) swarming motility
E) produces water soluble pigments
F) cannot utilize citrate
G) oxidase positive

Answer: D

(Year Posted:UI  393)

 

Key Code: B

A 70-year-old male, who is a chain-smoker, complains of fever, diarrhea, cough and chest pain. Evidence of pneumonia is seen by chest X-ray. Due to the inability of the patient to produce a sputum specimen, a transtrachial aspirate is obtained. No respiratory bacterial pathogen is isolated from aspirated fluid cultured on blood agar plates. However, poorly staining Gram-negative rods are isolated on buffered charcoal-yeast extract (BCYE) agar after three days of incubation. Which of the following antibiotics should the physician prescribe?

A) erythromycin
B) penicillin
C) carbenicillin
D) rifampin
E) streptomycin

Answer: A

(Year Posted:UI  394)

 

Key Code: B

Soft cheese imported from Mexico was implicated as the vehicle in an outbreak of meningitis and bacteremia that occurred among attendees of a large company picnic. Three of the 6 affected individuals were pregnant women. One of the victims had AIDS. Gram positive, non-spore forming rods were isolated from the cheese that had been stored in the cold. The MOST LIKELY organism responsible for this outbreak is

A) Bacillus cereus
B) Brucella abortus
C) Brucella melitensis
D) Clostridium perfringens
E) Listeria monocytogenes
F) Staphylococcus aureus
G) Mycobacterium kansasii

Answer: E

(Year Posted:UI  395)

 

Key Code: B

Use the answer choices below to answer questions (choose the ONE BEST answer)

A) Bordetella pertussis
B) Pseudomonas aeruginosa
C) Corynebacterium diphtheriae
D) Hemophilus influenzae type b
E) Legionella pneumophila
F) Neisseria meningitidis
G) Escherichia coli
H) Klebsiella pneumoniae
I) Bacillus anthracis
J) Listeria monocytogenes

 

__D__ may colonize the nasopharynx and causes inflammation and swelling of the epiglottis
__A__ colonizes the nasopharnyx and produces toxins that kill ciliated epithelial cells, causes edema locally, and induces lymphocytosis systemically
__G__ strains colonize the urinary tract and those expressing the P pilus are more likely to progress to pyelonephritis
__E__ colonizes environmental amoebae
__B__ lower respiratory tract colonization induces alginate capsule synthesis
__C__ colonizes the nasopharynx, produces a grayish membrane across the pharynx, produces toxin which acts systemically
__I__ wound infection, colonization, elaboration of toxins and the formation of a black eschar at the site of inoculation


(Year Posted:UI  396)

 

Key Code: B

Use the answer choices below to answer questions (choose the ONE best answer, answers may be used more than once)

A) Staphylococcus aureus
B) Staphylococcus epidermidis
C) Staphylococcus saprophyticus
D) Streptococcus agalactiae
E) Streptococcus pneumoniae
F) Streptococcus pyogenes
G) Enterococcus fecalis

 

__D__ Colonizes the vaginal tract and infects neonates during passage through the birth canal
__F__ Colonizes the skin, causes impetigo, and is cleared by the host inflammatory response; three weeks later the host may develop edema, hematuria, and proteinuria
__A__ Colonizes a small wound on the skin; scalded skin syndrome develops
__C__ Colonizes and causes UTI's in young women in particular
__E__ Colonizes the upper respiratory tract and extends to the middle ear
__E__ Colonizes the upper respiratory tract of adults and extends to the CNS
__B__ Colonizes a small wound on the skin; travels to damaged heart valves where it colonizes and leads to a slowly developing, chronic illness
__G__ Colonizes the urinary tract in a catheterized patient with a history of rheumatic heart disease; travels to damaged heart valves where it colonizes and leads to a slowly developing, chronic illness


(Year Posted:UI  397)

 

Key Code: B

A 15-year-old female presented with fever, headache and a non-productive cough. Penicillin was prescribed and the patient was sent home. Two weeks later, she returned with similar symptoms. A Gram stain and routine culture of the patient's sputum revealed only normal mouth flora. Sputum was then cultured on specialized medium containing sterols, and after two days tiny colonies were visible under a microscope. Which one of the following organisms did the physician suspect was the cause of the patient's pneumonia?

A) Corynebacterium diphtheriae
B) Hemophilus influenzae type b
C) Legionella pneumophila
D) Mycoplasma pneumoniae
E) Chlamydia pneumoniae
F) Ureaplasma urealyticum

Answer: D

(Year Posted:UI  398)

 

Key Code: B

Sera from individuals immunized with the recommended doses of the vaccine to prevent diphtheria should

A) kill Corynebacterium diphtheriae
B) neutralize diphtheria toxin
C) prevent colonization of the upper respiratory tract by Corynebacterium diphtheriae
D) promote increased uptake of Corynebacterium diphtheriae by PMNs
E) stimulate microbicidal activity of macrophages against Corynebacterium diphtheriae

Answer: B

(Year Posted:UI  399)

 

Key Code: B

A young army recruit presents at a sexually transmitted disease (STD) clinic with acute urethritis. A Gram-stained preparation of his urethral exudate reveals neutrophils with intracellular Gram-negative diplococci. The patient is treated with ceftriaxone and sent home. He is requested to return in one week so that a urethral culture can be obtained to test for proof of antibiotic cure. Which ONE of the following culture media should be used for the follow-up culture?

A) Blood agar
B) Bordet Gengou agar
C) MacConkey agar
D) Thayer Martin agar
E) Serum tellurite agar

Answer: D

(Year Posted:UI  400)