Multiple Choice Questions Database

 

Key Code: P, Key Code: B

Which one of the following associations between organism and risk factor is INCORRECT

A) Giardia - camping
B) Salmonella - eggs
C) Shigella - surface water
D) Clostridium difficile - antibiotic use
E) E. coli 0157 - undercooked hamburger

Answer: C

 

(Year Posted:  UI  901)

 

Key Code: B, Key Code: V

Patient D.N. has had several affairs over the last 12 months. He now develops one painless genital ulcer along the coronal sulcus of the penis. He comes to your office for treatment. Which of the following organisms MOST LIKELY produced his ulcer?

A) Chlamydia trachomatis
B) Herpes simplex II
C) Haemophilus ducreyi
D) Neisseria gonorrhoeae
E) Treponema pallidum

Answer: E

 

(Year Posted: 2002 UI  902)

 

Key Code: B, Key Code: V

Which of the following statements correctly associates an organism and an intervention that will effectively diminish the rate of acquiring that STI?

A) Genital Herpes-visual inspection before a sexual encounter
B) Human Papilloma Virus-correct diaphragm insertion prior to a sexual encounter
C) Chlamydia trachomatis-azithromycin given promptly after a sexual assault
D) Hepatitis C-immunization at least 6 weeks before the sexual encounter
E) HIV-lab test results from one year ago stating partner is HIV seronegative

Answer: C

 

(Year Posted: 2002 UI  903)

 

Key Code: B

On January 10, a 34-year-old woman visited her 73-year-old father in the nursing home where he resided; she took her 2-year-old daughter with her. This man had been a life-long cigarette smoker and had developed a persistent smoker's cough. Due to recent restlessness and depression, he had been taking prescription sleeping medication for about a week. The day before the visit, the man's cough worsened greatly and by the time of the visit he had a fever of 101oF. The following morning his fever had risen to 102.5oF, and the cough had become productive. On the third day after the visit, the child developed severe rhinitis with a copious nasal discharge. Over the next several days, she became febrile (102oF) and developed a raking cough. Her breathing was labored and difficult. Based on age-related risk and overall incidence, if it turns out that both the grandfather and his 2-year-old granddaughter have pneumonias that are bacterial and due to the same agent, the agent MOST LIKELY is:

A) Mycoplasma pneumoniae
B) Streptococcus pneumoniae
C) Legionella pneumophila
D) Chlamydia pneumoniae
E) Pseudomonas aeruginosa

Answer: B

 

(Year Posted: 2002 UI  904)

 

Key Code: V

Culture and Gram stain show no evidence of a bacterial infection in the 2-year-old. If the girl's pneumonia is viral and unrelated to her grandfather's case, the MOST LIKELY cause is:

A) A rhinovirus
B) Influenza virus
C) Respiratory syncytial virus
D) Rotavirus
E) Epstein Barr virus

Answer: C

 

(Year Posted: 2002 UI  905)

 

Key Code: B

The agent of the elderly man's disease was eventually identified as Legionella pneumophila. To prevent additional cases from developing in his nursing home, the MOST helpful approach would be:

A) To immunize the other residents immediately
B) To prescribe prophylactic antibiotics for the other residents
C) To enforce a scrupulous hand washing requirement for the nursing home staff
D) To install a filtered air system throughout the nursing home
E) To inspect the plumbing and air handling systems for the organism and decontaminate them if necessary

Answer: E

 

(Year Posted: 2002 UI  906)

 

Key Code: P

A 29-year old man, who was diagnosed with AIDS, presents with chronic, recurrent profuse, nonbloody, watery diarrhea. The diarrhea has recurred over the past two months with intermittent moderate cramping, and previous treatments have not been effective. The patient is moderately dehydrated. The patient has no travel history for the last two years. Lab test reveals 5um oocysts in the acid-fast stain of the stool sample. Which of the following is the MOST LIKELY cause of the man's illness?

A) Isospora belli
B) Giardia lamblia
C) Blastocystis hominis
D) Cyclospora cayetanensis
E) Cryptosporidium parvum

Answer: E

 

(Year Posted: 2002 UI  907)

 

Key Code: I

Individuals who have red blood cells of type A have isoagglutinins (alloantibodies) that react with the red blood cells of individuals who are type B and vice versa. Individuals who have red blood cells of type AB have no isoagglutinins and those with type O red blood cells have alloantibodies to both A and B red blood cells. Isoagglutinins are

A) secretory IgA antibodies produced by gut mucosa in response to food antigens
B) IgG antibodies produced by plasma cells against foreign blood group antigens
C) IgE antibodies that cause serum sickness
D) cross-reactive IgM antibodies produced against GI bacteria
E) polyclonal antibodies directed against medications

Answer: D

 

(Year Posted: 2003 UI  908)

 

Key Code: I

When an Rh-negative pregnant woman is compatible in the ABO system with her Rh+ husband, her risk for Rh alloimmunization is 16%. When they are ABO-incompatible, the risk is:

A) 7%
B) 16%
C) 32%
D) 65%
E) 100%

Answer: A

 

(Year Posted: 2003 UI  909)

 

Key Code: I

A 2-year old boy is referred to the University Hospital with a history of recurrent otitis media, upper and lower respiratory infections, eczema, frequent nosebleeds and bloody diarrhea since the age of 6 months. He was a full-term baby delivered without complications. His immunizations are up-to-date. His CBC is normal, except for thrombocytopenia, 40,000/mm3; the platelets are abnormally small. Further investigations reveal normal levels of IgG, decreased levels of IgM, and increased levels of IgA and IgE. He has normal numbers of circulating B and T lymphocytes, with a normal distribution of CD4 and CD8 cells. However, when stimulated with mitogens, a poor 
proliferative response is noted. Although the boy's blood type is O, he has no anti-A or anti-B isohemagglutinins in his serum and he has failed to mount an immune response to pneumococcal and Hib vaccines. Two of his three brothers have similar disease. What is the MOST LIKELY diagnosis?

A) Severe combined immunodeficiency syndrome
B) Bruton's agammaglobulinemia
C) Wiskott-Aldrich syndrome
D) Hyper-IgM syndrome
E) DiGeorge Syndrome

Answer: C

 

(Year Posted: 2003 UI  910)

 

Key Code: B

A Gram-negative pleomorphic organism isolated from the CSF of an unimmunized toddler is likely to be:

A) Escherichia coli
B) Pasteurella multocida
C) Streptococcus pneumoniae
D) Haemophilus influenzae
E) Neisseria meningitidis

Answer: D

 

(Year Posted: 2003 UI  911)

 

Key Code: B

A 45-year-old man, who had been diagnosed with AIDS presented with fever, fatigue, night sweats, cough productive of blood-tinged sputum, and weight loss. Microscopic examination of his sputum stained by Ziehl-Neelsen method revealed slender red-staining rods. Which of the following is the most appropriate conclusion? The patient's lung disease is

A) Bacillus Calmette-Guerin
B) Pneumocystis carinii
C) Acid-fast bacterium
D) Mycobacterium tuberculosis
E) Mycobacterium avium-intracellulare complex (MAC)

Answer: C

 

(Year Posted: 2003 UI  912)

 

Key Code: B

A 12-year old boy has a one-day history of severe right-sided abdominal pain, diarrhea, and fever. Based on the history and physical exam, acute appendicitis is strongly suspected. CT scan shows a normal appendix and enlargement of lymph nodes in the terminal ileum consistent with adenitis. His stool is positive for leukocytes and an enteric pathogen that grows at 40C. Infection with which of the following organisms is

A) Yersinia enterocolitica
B) Clostridium perfringens
C) Clostridium difficile
D) Trophermyma whippleii
E) Yersinia pseudotuberculosis

Answer: A

 

(Year Posted: 2003 UI  913)

 

Key Code: M

A 5-year old boy living in rural Missouri is brought to pediatrician's office, because his parents are concerned about his "puffy" appearance and tea-colored urine. His history is remarkable for impetigo, from which he recovered two weeks ago. On physical examination, the child is edematous, and his blood pressure is 150/100 mmHg. Creatinine clearance is mildly reduced. Both antistreptolysin O and anti-DNAse titers are elevated. Additional studies reveal that the patient's serum has

A) low levels of M protein
B) high levels of circulating streptokinase
C) low levels of C3
D) high levels of circulating streptolysin O
E) Streptococcus pyogenes, serotype M12

Answer: C

 

(Year Posted: 2003 UI  914)

 

Key Code: B

An 18-year old woman has a 1-day history of urinary frequency and dysuria. She is afebrile, and physical exam is negative, except for suprapubic tenderness. Urinalysis shows pyuria and bacteruria. Which of the following is

A) Hematogenous transmission of E. coli to bladder mucosa
B) Vesicoureteral reflux
C) Overgrowth of vaginal Lactobacillus
D) Contamination of the urethral os by normal skin flora
E) Colonization of the introitus by fecal flora

Answer: E

 

(Year Posted: 2003 UI  915)

 

Key Code: B

A 63-year-old man, who had undergone a gangrenous appendectomy, developed peritonitis. The culture of the peritoneal fluid was positive for Bacteroides fragilis, and he was placed on a 7-day-course of clindamycin. On day 5, the patient developed abdominal cramps and profuse watery diarrhea. Flexible sigmoidoscopy was performed, which revealed yellow-white adherent plaques varying in size from 5 to 10 mm in diameter and interspersed with inflamed hyperemic mucosa. What laboratory test would you order to confirm the diagnosis?

A) Culture on Salmonella-Shigella medium
B) ELISA test for detection of exotoxins A and B
C) Culture on TCBS medium to isolate Vibrio cholerae
D) Stool examination for Entamoeba histolytica
E) Antibiotic susceptibility testing

Answer: B

 

(Year Posted: 2003 UI  916)

 

Key Code: M

Which of the following is the pathomechanism employed by the causative agent implicated in the preceding clinical scenario?

A) The toxin produced by the bacterium ADP-ribosylates Gs protein and stimulates synthesis of cAMP
B) The bacterium causes colonic ulceration by direct invasion of the mucosa, followed by horizontal spread (transfection)
C) The trophozoites invade the colonic mucosa and secrete necrotizing enzymes
D) The toxin produced by the organism ADP-ribosylates Rho protein and causes actin depolymerization
E) The agent parasitizes mononuclear cells and causes granuloma formation

Answer: D

 

(Year Posted: 2003 UI  917)

 

Key Code: B

A 3-year old boy was hospitalized in the ICU at the Scottish Rite Children's Hospital. During a family outing to White Water Park, he had swallowed contaminated water in the kiddie pool. By next day, he developed abdominal cramps, vomiting, and bloody diarrhea, followed by kidney failure. His peripheral blood smear is shown below. Which of the following contributed

A) DIC
B) E.coli 0157:H7 septicemia
C) Shiga-like toxin
D) An ADP-ribosylating toxin
E) A superantigen

Answer: C

 

(Year Posted: 2003 UI  918)

 

Key Code: P

A 30-year old patient with AIDS develops pruritic rash and pulmonary infiltrate with eosinophilia (PIE) syndrome, followed by colicky abdominal pain, nausea, and vomiting. The patient's stool and duodenal fluid reveal larvae of a small (2 mm) round worm consistent with

A) Ancylostoma duodenale
B) Ascaris lumbricoides
C) Strongyloides stercoralis
D) Trichuris trichiura
E) Necator americanus

Answer: C

 

(Year Posted: 2003 UI  919)

 

Key Code: P

A contaminated municipal water supply was implicated in a recent outbreak of infectious diarrhea. Thousands of people developed cholera-like diarrhea, fever, abdominal pain, anorexia, nausea, and vomiting. Acid fast staining of the stool samples revealed red oocysts measuring 5 to 7 (m in diameter. What was the

A) Cryptosporidium parvum
B) Entamoeba histolytica
C) Isospora belli
D) Giardia lamblia
E) Cyclospora cayetanensis

Answer: A

 

(Year Posted: 2003 UI  920)

 

Key Code: V

A 2-year old boy is hospitalized because of fever, vomiting, and watery diarrhea. Latex agglutination test of his stool sample is positive for a wheel-like RNA virus measuring 75 nm in diameter. What is the

A) Viral infection of crypt cells results in their inability to replace lost enterocytes
B) Viral infection of mature enterocytes results in malabsorption
C) Viral infection of crypt cells results in malabsorption
D) Viral infection of mature enterocytes results in their inability to replace lost crypt cells
E) Viral infection of M cells resulting in loss of mucosa associated immunity

Answer: B

 

(Year Posted: 2003 UI  921)

 

Key Code: V

A 12-month old girl develops numerous vesicles on the lips and around the mouth as well as on the gingiva, tongue, and oral mucosa. The vesicles rupture within 24 hours, leaving painful ulcerative lesions. What is the

A) Herpes zoster virus
B) Herpes simplex virus type 1
C) Herpes simplex virus type 2
D) Epstein Barr virus
E) Candida albicans

Answer: B

 

(Year Posted: 2003 UI  922)

 

Key Code: V

In the aftermath of the recent terrorist attack on the United States, the Red Cross organized a nationwide blood drive. One of the UMHC doctors was among many responders willing to donate her blood. However, she soon learned that her blood had been discarded, because the screening test had revealed the presence of IgG antibodies against hepatitis B surface and core antigens. What is the

A) She has developed an acute hepatitis B
B) She has chronic active hepatitis B
C) She has developed immune-mediated liver damage
D) She has a 1% chance for developing hepatocellular carcinoma
E) She has protective immunity against hepatitis B

Answer: E

 

(Year Posted: 2003 UI  923)

 

Key Code: M

An environmental microbiologist collected a water sample from an air conditioning cooling tower that was located near the UNMC campus. One of the organisms that was found living in the water was viewed under a dark field microscope and was observed to have a distinct nucleus, including a nuclear membrane. What other statement from the following list

A) It is susceptible to penicillin
B) It has at least one linear chromosome
C) It has only 70S ribosomes in the cytoplasm
D) It can easily pass through a 0.22 It can easily pass through a 0.22 um pore of a filter
E) Its cell wall has a complex chemical and architectural structure

Answer: B

 

(Year Posted:UI  924)

 

Key Code: M

A Gram stain was performed on an unknown organism in a student microbiology lab. After viewing the slide, only blue bacilli were seen. From the following list, what is the most likely identification?

A) Escherichia coli
B) Clostridium perfringens
C) Mycoplasma pneumoniae
D) Pseudomonas aeruginosa
E) Mycobacterium tuberculosis

Answer: B

 

(Year Posted:UI  925)

Key Code: M

Infection with E. coli O157:H7 can result in a severe, life-threatening disease. Based solely on the serotype designation, what else must be TRUE for this organism?

A) It is motile
B) It is encapsulated
C) It is a facultative intracellular parasite
D) It possesses teichoic acids in its cell wall
E) It contains sterols in its cytoplasmic membrane

Answer: A

 

(Year Posted: 2003 UI  926)

 

Key Code: M

Specific antisera (antibodies) were prepared against a structural component of a particular species of pathogenic bacteria. When this antiserum was mixed with a suspension of the bacteria, there was a positive quellung reaction. Assuming this structural component is a virulence factor, what is its MOST important function?

A) Tissue toxicity
B) Fever production
C) Adherence to host tissue
D) Resistance to phagocytosis
E) Induction of cytokine secretion from macrophages

Answer: D

 

(Year Posted: 2003 UI  927)

 

Key Code: B

Some bacteria, such as Neisseria gonorrhoeae, undergo antigenic variation (also called phase variation) of the pili or outer membrane proteins. A consequence of such antigenic or phase variation is:

A) Enhanced phagocytosis
B) Inability to adhere to tissues
C) Reinfection with the same strain
D) Spontaneous recovery from the infection
E) Conversion from pathogenic to nonpathogenic

Answer: C

 

(Year Posted: 2003 UI  928)

 

Key Code: M

Gram negative bacteria are not affected by lysozyme as readily as Gram positive bacteria. Which of the following is responsible for this natural resistance?

A) Lipopolysaccharide
B) Transpeptidase
C) Peptidoglycan
D) Teichoic acid
E) Porin

Answer: E

 

(Year Posted: 2003 UI  929)

 

Key Code: B

In the clinical microbiology laboratory, a senior medical student was viewing several previously Gram stained slides. He said that one of the slides looked like E. coli. A medical technologist checked the code on the slide and said, "It's an obligate anaerobe". Which one of the following is the MOST LIKELY identification of the organism?

A) Bacteroides fragilis
B) Actinomyces israelii
C) Clostridium septicum
D) Propionibacterium acnes
E) Peptostreptococcus anaerobius

Answer: A

 

(Year Posted: 2003 UI  930)

 

Key Code: M

Penicillin can eventually lead to the death of susceptible bacteria. Before this happens, the penicillin must first bind to:

A) Lipopolysaccharide
B) Transpeptidase
C) Peptidoglycan
D) Teichoic acid
E) Porin

Answer: B

 

(Year Posted: 2003 UI  931)

 

Key Code: B

A recent immigrant from central Africa presented to the emergency room in obvious respiratory distress. A throat swab was obtained, streaked onto various kinds of bacteriological media, and incubated. One of the bacterial colonies was stained with methylene blue and viewed microscopically. Small red intracellular granules were observed. Based on this information, this patient may have:

A) A Pseudomonas infection
B) "Strep" throat
C) Diphtheria
D) Influenza
E) Anthrax

Answer: C

 

(Year Posted: 2003 UI  932)

 

Key Code: M

A mutant of Listeria monocytogenes, a Gram-positive organism that can cause meningitis, was no longer able to obtain iron very efficiently. What is the MOST logical explanation?

A) It lacked an O antigen
B) It lacked teichoic acids
C) It was unable to synthesize siderophores
D) Iron was unable to bind to the glycocalyx
E) The porins would no longer allow iron transport

Answer: C

 

(Year Posted: 2003 UI  933)

 

Key Code:M

Which one of the following is an example of quorum sensing?

A) The death of a population of bacteria as they enter the death and decline phase
B) An increase in the growth rate of all the bacteria when they are grown at 370 C instead of 200C
C) The simultaneous production of an exotoxin by all the bacterial cells when the population reaches a specific size
D) The swimming of a population of bacteria toward the intestinal epithelium in response to the release of chemotactic chemicals
E) The induction of heparinase in all the bacteria when they are switched from growing on glucose to growing on heparin

Answer: C

 

(Year Posted: 2003 UI  934)

 

Key Code: B

After surgery in a case of acute appendicitis, a specimen from the diseased appendix was submitted to the clinical microbiology laboratory. On visual inspection of the specimen, small yellow granules were observed that resembled sulfur. Which description of the Gram stain best fits this organism?

A) Gram-positive cocci in chains
B) Gram-positive cocci in clusters
C) Gram-positive branching bacilli
D) Gram-negative pleomorphic bacilli
E) Gram-negative fusiform (pointed ends) bacilli

Answer: C

 

(Year Posted: 2003 UI  935)

 

Key Code: M

Bordetella pertussis is a small Gram-negative coccobacillus that is the cause of whooping cough. Although it is also an obligate aerobe, it is theoretically possible to grow it under anaerobic conditions. How?

A) Grow it under fermentative conditions
B) Block glycolysis so that it cannot make pyruvic acid
C) Give it an organic compound as its only nutrient and withhold oxygen
D) Give it an organic substrate such as pyruvic acid as the final electron acceptor
E) Grow it in the presence of an alternative terminal electron acceptor such as nitrate

Answer: D

 

(Year Posted: 2003 UI  936)

 

Key Code: M

In bacterial conjugation between an F+ (F positive) cell and an F- (F minus) cell, what happens to the F+ cell after conjugation is completed?

A) It undergoes autolysis
B) t is converted into an F- cell
C) It is converted into an Hfr cell
D) Nothing, it remains as an F+ cell
E) The F plasmid becomes an episome

Answer: D

 

(Year Posted: 2003 UI  937)

 

Key Code: M

In conjugation between an Hfr cell and its recipient cell, what typically happens to the recipient cell?

A) It remains as an F- cell
B) It is converted into an F- cell
C) It is converted into an F+ cell
D) It is converted into an Hfr cell
E) The F plasmid becomes an episome

Answer: A

 

(Year Posted: 2003 UI  938)

 

Key Code: M

In tracking down the specific physical location of a gene that codes for beta-lactamase production in a plasmid-free strain of Staphylococcus aureus, some contradictory results were obtained. In some clones, the gene appeared to be in one location on the chromosome, but in other clones the gene was found in several additional locations on the chromosome. How can this best be explained?

A) The cells were lysogenic
B) The gene was part of an F factor
C) The gene was part of a transposon
D) This was an Hfr strain of S. aureus
E) The strain is infected with a prophage

Answer: C

 

(Year Posted: 2003 UI  939)

 

Key Code: M

In transduction, DNA transfer requires what?

A) F- cells
B) F+ cells
C) Sex pili
D) Episomes
E) Bacteriophages

Answer: E

 

(Year Posted: 2003 UI  940)

 

Key Code: M

In a microbiology research lab, it was found that a strain of Yersinia pestis produced a particular enzyme only if it was infected with a specific bacteriophage. This is MOST LIKELY an example of:

A) Homologous recombination
B) Lysogenic conversion
C) Hfr insertion
D) Transfection
E) Translation

Answer: B

 

(Year Posted: 2003 UI  941)

 

Key Code: M

DNAase (or DNASE) is an enzyme that can degrade free DNA that is in solution. Which one of the following can be inhibited if DNAase is added to a mixture of bacteria?

A) Transformation
B) Transposition
C) Transduction
D) Conjugation
E) Lysogeny

Answer: A

 

(Year Posted: 2003 UI  942)

 

Key Code: M

In the following diagram, A, B, C, and D represent bacterial isolates that were isolated from four different patients and spotted onto blood agar plates. The numbers under each plate refer to micrograms of antibiotic per milliliter. What is the minimum bactericidal concentration (MBC) of organism D?

 

A) Grow it under fermentative conditions
B) Block glycolysis so that it cannot make pyruvic acid
C) Give it an organic compound as its only nutrient and withhold oxygen
D) Give it an organic substrate such as pyruvic acid as the final electron acceptor
E) Grow it in the presence of an alternative terminal electron acceptor such as nitrate

Answer: E

 

(Year Posted: 2003 UI  943)

 

Key Code: M

From the following information and diagram, for which antibiotic is the organism resistant?

 

ResistantIntermediateSusceptible

Penicillin< 1011-1213

Clindamycin< 1213-1718

Tetracycline< 1516-2122

Streptomycin<   910-1415

A) Penicillin
B) Clindamycin
C) Tetracycline
D) Streptomycin
E) It is resistant to all four antibiotics

Answer: B

 

(Year Posted: 2003 UI  944)

 

Key Code: M

A rookie graduate student working with Streptococcus pneumoniae in a biohazard hood was trying to determine the cause of death of all his bacteria during some experiments. He analyzed their DNA and found many thymine dimers. The cause of death was MOST LIKELY

A) Iodine
B) Phenol
C) UV light
D) Gamma rays
E) Hydrogen peroxide

Answer: C

 

(Year Posted: 2003 UI  945)

 

Key Code: M

This same graduate student needed to sterilize some plastic centrifuge tubes that were to be used in a laboratory experiment the following day. From the following list of methods available to him, which one should he choose?

A) UV light
B) Autoclaving
C) Lyophilization
D) Dry heat sterilization
E) Gamma ray irradiation

Answer: E

 

(Year Posted:UI  946)

 

Key Code: M

A protein chemist received some dead bacteria from a company that makes antimicrobial agents. The chemist analyzed the bacterial proteins and found that many of the tyrosines had been modified. There was also evidence of some oxidation. Which one of the following agents killed the bacteria?

A) Iodophor
B) Merthiolate
C) Silver nitrate
D) Ethylene oxide
E) Glutaraldehyde

Answer: A

 

(Year Posted:UI  947)

 

Key Code: M

From the following list, choose the best method to sterilize a highly sophisticated and fragile probe that is being sent to Jupiter's moon, Europa, to search for life

A) UV light
B) Autoclave
C) Lyophilization
D) Formaldehyde
E) Ethylene oxide

Answer: E

 

(Year Posted: UI  948)

 

Key Code: M

In a laboratory experiment, a strain of E. coli was transferred from a growth medium containing only fructose as the carbon and energy source into a new growth medium containing a large complex polysaccharide (heparin) as the only carbon and energy source. This strain of E. coli had the genetic capability to grow on both of these substrates. Upon transfer to this new complex medium, the bacteria initially enter which phase of growth?

A) Lag
B) Log
C) Stationary
D) Death and Decline

Answer: A

 

(Year Posted:UI  949)

 

Key Code: M

From the previous question, which one of the following would you choose as the terminal electron acceptor in order to maximize the total amount of ATP produced?

A) Nitrate
B) Sulfate
C) Oxygen
D) Acetyl CoA
E) Pyruvic acid

Answer: C

 

(Year Posted:UI  950)

The next 2 questions are based upon the following drawing of a bacterial cell wall:

 

Key Code: M

Assuming that this cell wall is from a bacterium susceptible to penicillin, what structure is MOST affected by the penicillin?

A) A
B) B
C) C
D) D
E) E

Answer: D

 

(Year Posted: 2003 UI  951)

 

Key Code: M

What structure (A, B, C, D, or E) results in the release of tumor necrosis factor (TNF) from macrophages if the bacteria lyse in the blood stream?

A) A
B) B
C) C
D) D
E) E

Answer: A

 

(Year Posted: 2003 UI  952)

 

Key Code: B

Which one of the following characteristics applies to the organism MOST commonly isolated from blood culture bottles?

A) Coagulase positive
B) Optochin susceptible
C) Gram-positive cocci in pairs
D) Inhibited by sodium chloride
E) Identified by lactose fermentation

Answer: A

 

(Year Posted: 2003 UI  953)

 

Key Code: B

Blood from a patient with a post-surgical abdominal infection was submitted to the laboratory for culture. The isolated organism would not grow in the presence of oxygen. Subsequently it was shown to produce endospores. Which additional characteristic would you expect for this organism?

A) It is acid-fast
B) Its cell wall contains lipoteichoic acid
C) It commonly causes endotoxic shock
D) Gram stain shows characteristic metachromatic granules
E) The peptidoglycan in the periplasmic space is very thin in thickness

Answer: B

 

(Year Posted: 2003 UI  954)

 

Key Code: M

In a microbiology genetics experiment, it was found that a gene coding for ampicillin resistance could be transferred from one strain of E. coli to another strain when both strains were suspended in nutrient broth. On further investigation, it was found that if the two strains were kept separated in the broth by a filter (0.22um pore size), gene transfer did not occur. This genetic exchange is an example of:

A) Conjugation
B) Transformation
C) Lysogenic conversion
D) Specialized transduction
E) Generalized transduction

Answer: A

 

(Year Posted: 2003 UI  955)

 

Key Code: M

Some strains of Streptococcus pyogenes can produce an erythrogenic toxin that may result in scarlet fever. Research has shown that this toxin is coded for by a toxin gene carried by a bacteriophage. In describing this phenomenon to a colleague, which one of the following terms would you MOST LIKELY use in your explanation?

A) Hfr
B) Plasmid
C) Lysogenic
D) Transposon
E) Homologous

Answer: C

 

(Year Posted: 2003 UI  956)

 

Key Code: M

In analyzing the genotypes after transduction experiments, it was observed that all the transduced cells had genetic sequences from the donor cells that were inserted only between the same two genes on the chromosome. This is MOST LIKELY an example of:

A) Hfr conversion
B) Transformation
C) Phage conversion
D) Specialized transduction
E) Generalized transduction

Answer: D

 

(Year Posted: 2003 UI  957)

 

Key Code: B

A Gram-negative anaerobic rod was isolated from the abdominal cavity of a patient with a perforated colon. Assuming this is the MOST common anaerobe from such infections, what is the drug of choice?

A) Penicillin
B) Gentamicin
C) Vancomycin
D) Azithromycin
E) Metronidazole

Answer: E

 

(Year Posted: 2003 UI  958)

 

Key Code: M

E. coli is a facultative anaerobe and Helicobacter pylori is microaerophilic. Assuming each can utilize glucose as both a carbon and an energy source, which one of the following would you predict if each were grown under optimal conditions for ATP production?

A) E. coli would make more ATP
B) H. pylori would make more ATP
C) Both would make the same amount of ATP
D) There is not enough information to make a prediction

Answer: C

 

(Year Posted: 2003 UI  959)

 

Key Code: M

With some species of bacteria, L-forms can be made in the laboratory. Which one of the following would be MOST useful for creating L-forms?

A) UV light
B) Penicillin
C) Cholesterol
D) Mycolic acid
E) Anti-LPS monoclonal antibody

Answer: B

 

(Year Posted: 2003 UI  960)

 

Key Code: B

A resident asked a medical student, who was on a third year rotation in OB/GYN, to discuss the significance of measuring a vaginal pH of 3.8 in one of the patients. The MOST correct response from the following list is:

A) She has candidiasis
B) Lactobacilli are present
C) The patient has bacterial vaginosis due to endogenous Gardnerella
D) She has an STD, most probably of bacterial rather than viral etiology
E) This is the normal pH due to the acidification of the mucus just prior to secretion

Answer: B

 

(Year Posted: 2003 UI  961)

 

Key Code: M

A cancer patient developed nosocomial sepsis and shock due to Stenotrophomonas (Xanthomonas) maltophilia. A characteristic of the bacterial product or component which is responsible for the shock is it:

A) Is also pyrogenic
B) Is a superantigen
C) Is easily inactivated by boiling
D) Can be actively secreted by other related bacteria
E) Can induce the immune system to synthesize protective antibodies

Answer: A

 

(Year Posted: 2003 UI  962)

 

Key Code: M

The physician of a patient with endocarditis requested the value for the minimum bactericidal concentration of the antibiotic she was using. The method of choice to determine this value is:

A) Colorimetric
B) Agar dilution
C) Broth dilution
D) Gradient diffusion (E-test)
E) Agar disc diffusion (Kirby-Bauer)

Answer: C

 

(Year Posted: 2003 UI  963)

 

Key Code: B

A patient with extensive burns developed an infection of the affected skin. A Gram-negative bacillus was isolated that was oxidase-positive and produced a bluish-green pigment on agar plates. This opportunistic pathogen is MOST likely:

A) Klebsiella
B) Salmonella
C) Escherichia coli
D) Proteus vulgaris
E) Pseudomonas aeruginosa

Answer: E

 

(Year Posted: 2003 UI  964)

 

Key Code: B

The parents of a five-month old boy bring their baby to the emergency room. The infant has signs and symptoms consisting of fever, constipation, hypotonia (decreased muscle tone), and droopy eyelids. His parents report he has not been eating well. An infectious disease is suspected. What is the MOST likely pathogen?

A) Enterococcus faecium
B) Clostridium botulinum
C) Staphylococcus aureus
D) Streptococcus pneumoniae
E) Group A strep (Streptococcus pyogenes)

Answer: B

 

(Year Posted: 2003 UI  965)

 

Key Code: B

A bacterium isolated in a microbiology research lab was found to produce a toxin that inhibited the release of the neurotransmitters glycine and gamma-aminobutyric acid. Disease in adults caused by this organism is MOST commonly acquired by:

A) arthropods
B) sexual contact
C) puncture wound
D) contaminated food
E) inhalation of droplets

Answer: C

 

(Year Posted: 2003 UI  966)

 

Key Code: B

A 19-year-old man required surgical repair of a fractured radius following a rollerblading accident. The patient developed redness and a yellowish discharge from the surgical site. A Gram stain of the pus revealed Gram-positive cocci. Colonies isolated from the pus were catalase and coagulase positive. Which of the following is the MOST LIKELY cause of infection?

A) Enterococcus faecalis
B) Streptococcus pyogenes
C) Staphylococcus epidermidis
D) Staphylococcus aureus
E) Haemophilus influenzae

Answer: D

 

(Year Posted: 2003 UI  967)

 

Key Code: B

A 17-year-old man with cystic fibrosis was admitted to the hospital with a brief history of fever, cough, and shortness of breath. A chest X-ray showed changes consistent with chronic infection and sputum Gram-stain reveals PMNs and many Gram-negative bacilli. The MOST LIKELY cause of his infection is:

A) Streptococcus pneumoniae
B) Haemophilus influenzae
C) Pseudomonas aeruginosa
D) Klebsiella pneumoniae
E) Mycoplasma pneumoniae

Answer: C

 

(Year Posted: 2003 UI  968)

 

Key Code: V

A 22-year old man complained of fever, sore throat, fatigue and loss of appetite. Physical examination detected enlarged lymph nodes and blood tests showed the presence of a large number of atypical lymphocytes as well as the presence of heterophile antibodies. The MOST LIKELY diagnosis is:

A) Acute T-cell leukemia
B) Strep throat
C) Mononucleosis caused by cytomegalovirus infection
D) Mononucleosis caused by Epstein-Barr virus infection
E) Herpes simplex virus type 1 infection

Answer: D

 

(Year Posted: 2003 UI  969)

 

Key Code: B

A 12-year-old girl developed the symptoms of acute renal failure. Physical examination revealed numerous skin lesions with serous exudate on her leg. Results of lab tests on the serous exudate showed Gram-positive, catalase negative cocci. Which of the following processes is MOST LIKELY responsible for the renal failure in this patient?

A) Deposition of M protein-containing immune complexes
B) Streptolysin O (SLO)-induced tissue damage
C) Self-attack by antibodies to SLO
D) Toxic shock-like syndrome
E) Cytokine release induced by pyrogenic exotoxin A

Answer: A

 

(Year Posted: 2003 UI  970)

 

Key Code: V

The patient was a 15-month-old girl who presented to her pediatricians office with fever of 39.20C, swollen lymph nodes, and a vesicular rash on her trunk and upper arms. The vesicles were at various stages of development, some newly formed and some erupted with crust formation. Select the MOST LIKELY infectious agent:

A) Smallpox
B) Staphylococcus aureus
C) Measles virus
D) Parvovirus B19
E) Varicella-zoster virus

Answer: E

 

(Year Posted: 2003 UI  971)

 

Key Code: B

A 9-year-old boy was transported by a philanthropic agency from Central Africa to Boston for surgical correction of trachoma. The MOST LIKELY etiology in this case is:

A) Person to person transmission of elementary bodies
B) Mother to newborn transmission of elementary bodies during childbirth
C) Inoculation of yeast by means of a penetrating injury
D) Dissemination of a congenital infection
E) Water contaminated with cysts

Answer: A

 

(Year Posted: 2003 UI  972)

 

Key Code: B

An 83-year-old woman was diagnosed with infective endocarditis following a lengthy period of low-grade fevers, night sweats, and weight loss. She had an impacted wisdom tooth extracted 3-weeks prior to her illness. She received no antibiotic prophylaxis following the dental procedure despite a history of rheumatic heart disease. A Gram-stain of a blood culture revealed Gram-positive cocci. Which of the following is the MOST LIKELY etiologic agent?

A) Staphylococcus aureus
B) Streptococcus viridans
C) Enterococcus faecalis
D) Staphylococcus epidermidis
E) Candida albicans

Answer: B

 

(Year Posted: 2003 UI  973)

 

Key Code: V

A 20-year-old man comes to your clinic complaining of anorexia (loss of appetite), weight loss and fatigue for about 2 weeks. On exam you find he is mildly jaundiced and his abdomen is tender in the right upper quadrant. On further questioning, you discover he had hives and joint pains in his hands about 3 weeks ago. IgM antibody to which of the following is MOST LIKELY to establish the diagnosis in this case?

A) Hepatitis A surface antigen
B) Hepatitis B core antigen
C) Hepatitis C surface antigen
D) Hepatitis B surface antigen
E) Hepatitis E core antigen

Answer: B

 

(Year Posted:UI  974)

 

Key Code: B

A woman in her third trimester of pregnancy sees her obstetrician with complaints of the "flu". She complained of headache, fatigue, muscle and joint ache. The physician orders rest. Two weeks later she delivers a stillborn with miliary-disseminated pyogranulomatous lesions on the body surface. A diagnosis of granulomatosis infantiseptica is made. The MOST LIKELY etiological agent is:

A) Neisseria gonorrhoeae
B) Treponema pallidum
C) Staphylococcus aureus
D) Listeria monocytogenes
E) Streptococcus agalactiae

Answer: D

 

(Year Posted:UI  975)

Key Code: B

An 87-year-old nursing home resident presented with confusion and fever. In the emergency room, he was found to have a fever of 1030F, blood pressure 100/50, pulse 110/min. Clinical examination revealed a normal chest examination, absence of cough, and an entirely normal abdominal exam. A urine specimen obtained by catheter revealed >100 WBC/field, occasional erythrocytes, and 2 proteinuria. Gram stain of the urine specimen revealed Gram-positive cocci. Culture is pending. The 
MOST LIKELY microorganism causing his illness is:

A) Staphylococcus saprophyticus
B) Escherichia coli
C) Pseudomonas aeruginosa
D) Candida albicans
E) Enterococcus faecalis

Answer: E

 

(Year Posted: 2003 UI  976)

 

Key Code: V

A 5-year old patient with sickle-cell anemia became infected with parvovirus B19. His red blood cell count dropped 0 a dangerous levels. This is the result of:

A) Deposition of immune complexes in the skin and joints
B) High fever
C) Virus replication in the liver and spleen
D) Virus replication in erythrocytes
E) Virus replication the bone marrow

Answer: E

 

(Year Posted: 2003 UI  977)

 

Key Code: B

A 2-year-old girl travels with her family to Maryland in June for vacation. A week later, the father finds a small (2 mm) black spot behind her ear that he thought was a scab. Four days later, a red enlarging circular lesion appears around the same ear and fades within a week. They return to Michigan and visit their Pediatrician who notes that the child's smile is not quite symmetrical. The MOST LIKELY diagnosis is:

A) Tinea capitis
B) Hypersensitivity to a mosquito bite
C) Lyme disease
D) Erythema infectiosum
E) Enteroviral exanthem

Answer: C

 

(Year Posted: 2003 UI  978)

 

Key Code: B

A19-year-old prostitute presented with a painful soft, ragged ulcer on the genitalia. Small Gram-negative coccobacilli were isolated the lesion. What is the MOST LIKELY pathogen causing this infection?

A) Bacteroides fragilis
B) Chlamydia trachomatis serovars D-K
C) Haemophilus ducreyi
D) Treponema pallidum
E) Gardnerella vaginalis

Answer: C

 

(Year Posted: 2003 UI  979)

 

Key Code: B

A 20-year-old female was seen in the Student Health Center because of frequent and painful urination. She had been sexually active since the age of 16. Her urine culture grew >100,000 CFU/ml on a blood agar plate. The isolate was Gram-negative, lactose-positive, and indole-positive. What is your diagnosis?

A) Staphylococcus aureus
B) Proteus mirabilis
C) Staphylococcus epidermidis
D) Escherichia coli
E) Staphylococcus saprophyticus

Answer: D

 

(Year Posted: 2003 UI  980)

 

Key Code: B

A neonatologist examined an 18-hour-old baby boy who was born the previous day to a woman who had ruptured membranes and was in labor for 20 hours. The physician diagnosed a septic syndrome and ordered an infectious disease work-up. The microbiology laboratory reported that the CNS culture from the spinal tap and the blood culture were growing aerobic, catalase negative, Gram-positive cocci. Based on the history and culture results, which of the following is the MOST LIKELY etiological agent?

A) Listeria monocytogenes
B) Staphylococcus aureus
C) Streptococcus agalactiae
D) Enterococcus faecalis
E) Escherichia coli

Answer: C

 

(Year Posted: 2003 UI  981)

 

Key Code: B

A 54-year old automobile executive became ill with severe, frequent, and watery diarrhea while returning to Detroit on an international flight. He presented himself to the Emergency Department of Detroit Receiving Hospital with severe dehydration and continuation of the watery diarrhea. A stool sample was sent for culture. The following morning, the microbiology laboratory reported oxidase positive, lactose negative colonies on MacConkey agar and growth of sucrose positive colonies on TCBS agar. The clinical history and preliminary laboratory data would be MOST consistent with infection by:

A) Salmonella enteritidis
B) Yersinia enterocolitica
C) Listeria monocytogenes
D) Entamoeba histolytica
E) Vibrio cholerae

Answer: E

 

(Year Posted: 2003 UI  982)

 

Key Code: B

A 7-year-old boy was seen at the pediatric clinic with a severe intestinal pain. The mother stated that the child had abdominal pain and cramping and a low fever for the past two days. The child developed bloody diarrhea with mucous but of little volume. A stool sample is examined and found to contain numerous PMNs. The microbiology preliminary report that is received the next day would be MOST LIKELY which of the following?

A) Oxidase positive, lactose positive, Gram-negative bacillus
B) Oxidase positive, lactose negative, Gram-negative bacillus
C) Oxidase negative, lactose positive, Gram-negative bacillus
D) Oxidase negative, lactose negative, Gram-negative bacillus
E) Oxidase positive, sucrose positive, Gram-negative bacillus

Answer: D

 

(Year Posted: 2003 UI  983)

 

Key Code: F

A 28-year-old man was diagnosed with chronic meningitis. A spinal tap and blood culture were collected. The calcafluor white stain revealed yeast on a smear made from the cerebrospinal fluid (CSF) sediment. Two days later, the microbiology laboratory reported that the blood cultures and CSF grew yeast, which are urease positive. The MOST LIKELY etiological agent is:

A) Coccidioides immitis
B) Cryptococcus neoformans
C) Candida albicans
D) Histoplasma capsulatum
E) Nocardia asteroides

Answer: B

 

(Year Posted: 2003 UI  984)

 

Key Code: B

A 43-year-old woman was admitted to the hospital because she was found to have right lower lobe pneumonia. Her teeth were badly decayed and she had a history of poorly controlled seizures. Antibiotic treatment using clindamycin was prescribed. Within three days, her pneumonia was much improved. However, by the 7th day of antibiotic therapy, she had recurrence of fever, diarrhea, and abdominal tenderness. The BEST course of action is to:

A) Draw blood cultures and increase the IV fluids
B) Evaluate the stool for toxin using EIA and change antibiotics to metronidazole
C) Send a stool sample for culture and change antibiotics to a quinolone
D) Send a stool sample for fecal leukocytes and treat with a different antibiotic only if it is positive

Answer: B

 

(Year Posted: 2003 UI  985)

 

Key Code: V

A 28-year-old high school teacher from the US was traveling in Thailand where she was bitten by a stray dog. The woman did not seek treatment initially, but visited a clinic in Bangkok one week later. The clinic she visited lacked vaccines. The woman returned to the US where she died from rabies. Which of the following treatments would have been necessary for her survival?

A) Administration of rabies virus vaccine
B) Immunization with anti-rabies immunoglobulin
C) Immediate cleansing of the wound after the bite
D) Administration of rabies vaccine and anti-rabies immunoglobulin within one week after the bite
E) Administration of acyclovir at the time of the bite

Answer: D

 

(Year Posted: 2003 UI  986)

 

Key Code: B

An 8-year-old boy living in a wooded area of Virginia suddenly developed fever, headache, and myalgia. On physical exam, a rash was noted on his wrists and ankles. Within hours, the rash spread to his trunk. No organisms were isolated from 3 sequential blood cultures. The child was treated with tetracycline and recovered. 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) Rickettsia prowazekii
C) Francisella tularensis
D) Rickettsia ricketssii
E) Yersinia pestis

Answer: B

 

(Year Posted: 2003 UI  987)

 

Key Code: F

A 45-year-old man with diabetes developed a chronic cough and intermittent fever. A chest radiograph resulted in a preliminary diagnosis of tuberculosis. However, the patient is tuberculin test negative. An employment history revealed that he is a heating contractor who installed ductwork on the roofs and in the attics of old buildings that were bird-nesting sites. Tissue biopsy from a pulmonary lymph node was taken. This specimen would MOST LIKELY reveal macrophages filled with:

A) Acid-fast bacilli
B) Yeast cells
C) Trophozoites
D) Merozoites

Answer: B

 

(Year Posted: 2003 UI  988)

 

Key Code: V

A 50-year-old divorced female complained of persistent irritation, soreness in the genital area of three days duration. After being celibate for three years, she reported that she became sexually active with her fianc two months previously. Physical examination revealed bilateral tender vesicles in the vulvar area. Tender lymphadenopathy was detected. Her fianc denied a history of genital herpes. Which test is most likely to provide a diagnosis of genital herpes?

A) Zanck test for oral cytopathology
B) Enzyme immunoassay
C) Genital lesion culture
D) Type specific herpes serology
E) Urine HSV-PCR

Answer: C

 

(Year Posted: 2003 UI  989)

 

Key Code: B

A 63-year-old man who had been released from prison in 1971 reported to the clinic with a chronic cough, night sweats and significant weight loss over the past 7 months. Microbiologic examination of sputum reveals acid-fast bacilli and a chest radiograph shows multiple granulomas in the man's lungs. The pathogen causing this patient's infection:

A) Initiates a persistent infection by releasing cytotoxins that kill macrophages
B) Initiates a persistent infection by preventing phagosome and lysosome fusion
C) Initiates a persistent infection by colonizing the dorsal root ganglia
D) Transiently infects pulmonary epithelium and is shed continuously
E) Transiently infects pulmonary epithelium and is shed intermittently

Answer: B

 

(Year Posted: 2003 UI  990)

 

Key Code: V

Last August, a 55-year old man attended a scientific conference at Cold Spring Harbor Laboratory, which is near Queens, New York. Shortly after his arrival back in Detroit, he developed high fever, headache, and a sore throat. He also developed the symptoms of encephalitis. Identify the MOST LIKELY etiologic agent that would be diagnosed using RT- PCR analysis

A) Ebola virus
B) Yellow fever virus
C) West Nile Virus
D) Hantavirus
E) Dengue virus

Answer: C

 

(Year Posted: 2003 UI  991)

 

Key Code: V

A recently graduated nurse accidentally sticks herself with the needle used to draw blood from a man admitted with jaundice. Which viral infection, most likely to be transmitted in this setting, could have been prevented by an earlier vaccination?

A) Hepatitis A
B) Hepatitis B
C) Hepatitis C
D) Hepatitis E
E) Hepatitis B and C

Answer: B

 

(Year Posted: 2003 UI  992)

 

Key Code: B

An 8-year-old girl was brought to the Emergency Department of Children's Hospital with bloody diarrhea and thrombotic thrombocytopenia purpura that eventually progressed to hemolytic uremia syndrome. A virulence factor of the MOST LIKELY etiologic agent is:

A) Cholera toxin
B) Shiga toxin
C) Heat stable toxin
D) Vi antigen
E) Cytotoxin B

Answer: B

 

(Year Posted: 2003 UI  993)

 

Key Code: M

Which of the preceding compounds is found in Gram positive but not Gram negative bacteria?

A) Glycoprotein
B) Lipopolysaccharide
C) Peptidoglycan
D) Phospholipid
E) Teichoic acid

Answer: E

 

(Year Posted: 2003 UI  994)

 

Key Code: M

Which of the preceding compounds is found in Gram negative but not Gram positive bacteria?

A) Glycoprotein
B) Lipopolysaccharide
C) Peptidoglycan
D) Phospholipid
E) Teichoic acid

Answer: B

 

(Year Posted: 2003 UI  995)

 

Key Code: B

Select the characteristic response of genetically sensitive bacteria after addition of penicillin at the arrow



Answer: C
 

(Year Posted: 2003 UI  996)

 

Key Code: B

Select the characteristic response of genetically sensitive bacteria after addition of tetracycline at the arrow



Answer: B
 

(Year Posted: 2003 UI  997)

 

Key Code: B

Select the characteristic response of genetically sensitive bacteria after addition of penicillin plus tetracycline at the arrow



Answer: B
 

(Year Posted:UI  998)

 

Key Code: B

If gentamicin is added at the arrow to a genetically sensitive E. coli growing in rich broth medium, what is the expected response when the culture is incubated anaerobically?



Answer: A
 

(Year Posted:UI  999)

 

Key Code: B

Which is involved in the pathophysiology of pneumococcal septicemia with meningitis and hypotension

A) Nitric oxide
B) IL-1, IL-6
C) TNF
D) Prostaglandins, endorphins
E) All of the above

Answer: E

 

(Year Posted:UI 1000)