Multiple Choice Questions Database

 

Key Code: B

German general Erwin Rommel, the “Desert Fox”, led the North African tank division during World War II. He was always seen in newsreels with a handkerchief pressed to his nose. This was not because of desert dust, but because of an infectious disease he had during that time (see Koda 1: Gram stained smear of the causative agent). He periodically returned to Berlin for treatment, leaving his troops without his brilliant leadership, which may have contributed to the Nazis’ defeat in North Africa. Later he was arrested by Gestapo for plotting to assassinate Hitler, but before an interrogation started, he suffered what was then reported as a “heart attack” and died. What was the most likely cause of general Rommel’s death?

A) Streptococcal toxic shock syndrome
B) Poststreptococcal acute rheumatic fever
C) Cardiomyopathy caused by diphtheria toxin
D) Endocarditis most likely caused by Staphylococcus aureus
E) Myocardial infarction caused by the dislodged diphtheritic membrane

 

      Koda 1


Answer: C

(Year Posted:UI  401)

 

Key Code: B

A 14 year-old boy who had been diagnosed with cystic fibrosis developed pneumonia. His sputum was positive for small Gram-negative pleomorphic organisms which grew on a  chocolate agar plate (Koda 2), but failed to grow on blood agar. Which of the following is the most likely cause?

A) Pseudomonas aeruginosa
B) Neisseria meningitidis
C) Pseudomonas cepacia
D) Haemophilus influenzae

 

Koda 2


Answer: D

(Year Posted:UI  402)

 

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 >105/ml of the organism shown on (Koda 3 blood agar plate). The isolate was coagulase negative and novobiocin resistant. What is your diagnosis?

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

 

Koda 3


Answer: E

(Year Posted:UI  403)

 

Key Code: B

A 17-year-old high school student presents with swollen and painful joints on his lower extremities. The causative agent (Koda 4: Gram stained smear of the aspirate) grew on Thayer-Martin agar, was oxidase positive and utilized glucose. What is the most likely diagnosis?

A) Yersinia enterocolitica
B) Neisseria gonorrhoeae
C) Staphylococcus epidermidis
D) Neisseria meningitidis

 

Koda 4


Answer: B

(Year Posted:UI  404)

 

Key Code: B

KODAs 5 and 6 represent a Gram stained smear of the pathogen and clinical manifestations associated with it. What is the organism?

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

 

 

Koda 5

 Koda 6


Answer: E

(Year Posted:UI  405)

 

Key Code: B

Several children had been hospitalized with bloody diarrhea and severe hematologic abnormalities (Koda 7: peripheral blood smear); a 4-year-old girl died shortly after hospitalization. An epidemiologic investigation established that all the patients developed symptoms following consumption of Odwalla apple juice. The organism responsible for the outbreak grew colorless colonies on a sorbitol-MacConkey agar plate. What was the cause of the outbreak?

A) Enterotoxigenic E. coli
B) Listeria monocytogenes
C) Enterohemorrhagic E. coli
D) Salmonella typhi
E) Enteroinvasive E. coli

 

Koda 7


Answer: C

The disease is mediated by which of the following mechanisms?

A) Direct invasion and systemic spread of infection
B) Inflammatory response triggered by the action of a toxin-superantigen
C) The action of a hemolysin that facilitates the evasion of the immune system
D) Endothelial damage caused by a toxin that has an N-glycosidase activity
E) Systemic effect of heat-labile and heat-stable ADP-ribosylating enzymes


Answer: D

(Year Posted:UI  406)

 

Key Code: B

The patient presented with the following lesions (Koda 8). The specimen taken from the lesions grew characteristic colonies on mannitol salt (Koda 9) and blood agar plates and clumped when mixed with rabbit plasma. What is your diagnosis?

A) Scalded skin syndrome
B) Toxic shock syndrome
C) Carbunculosis
D) Erysipelas
E) Impetigo

Koda 8

Koda 9


Answer: A

(Year Posted:UI  407)

 

Key Code: B

First, the child developed fever and rash with characteristic “strawberry tongue”, and a few days later, the mother presented with severe facial swelling (KODAs 10 and 11). What is the most likely diagnosis for the child’s and the mother’s conditions?

A) Staphylococcal toxic shock syndrome and folliculitis
B) Streptococcal toxic shock syndrome and boil
C) Meningococcemia and pyoderma
D) Scarlet fever and erysipelas
E) Meningitis and impetigo

Koda 10

Koda 11


Answer: D
 

The causative agent isolated from both patients (Koda 12: blood agar plate) was

A)  Staphylococcus aureus
B) Streptococcus pyogenes
C) Haemophilus influenzae
D) Pasteurella multocida
E) Neisseria meningitidis

 

                                                   Koda 12


Answer: B

(Year Posted:UI  408)

 

Key Code: B

Match the MOST EFFECTIVE host protective immune mechanism with each organism below. An answer may be used more than once

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

 

__E__ Streptococcus pneumoniae
__D__ Clostridium tetani
__D__ Clostridium botulinum
__C__ Brucella abortus
__E__ Neisseria meningitidis
__C__ Legionella pneumophila
__D__ Corynebacterium diphtheriae


(Year Posted:UI  409)

 

Key Code: B

Use the answer choices below to match the toxin mechanism of action to the pathogenic process described for question bellow (an answer may be used more than once)

A) ADP-ribosylates a G protein of the adenylate cyclase complexs
B) ADP-ribosylates EF2 needed for protein synthesis
C) Binds to MHC class II molecules on antigen presenting cells and to the T cell receptor; functions as a potent polyclonal T cell activator
D) Prevents release of glycine and other inhibitory neurotransmitters
E) Prevents acetylcholine release
F) Membrane action results in host cell lysis

 

__C__ Bacteria colonize the vaginal tract of menstruating women using superadsorbent tampons; toxin production leads to a severe systemic illness
__A__ Bacteria must adhere in the small intestine where they elaborate toxin responsible for disease symptoms
__B__ Bacteria adhere in the respiratory tract where they replicate; elaboration of toxin both kills cells locally and has systemic toxic effects, particularly on heart tissue 
__D__ Colonization of a puncture wound leads to local multiplication of bacteria that produce toxin that travels by retrograde axonal transport to the CNS
__E__ Ingestion of toxin from contaminated food is all that is required; toxin is absorbed from the intestine and travels to the CNS where its principal effects are seen
__A__ Bacteria enters the respiratory tract where it adheres well to ciliated bronchial epithelial cells; among other affects one toxin produced may promote lymphocytosis
__B__ Bacteria infect a burn wound, elaborate a variety of extracellular products that have an effect on the host including an exotoxin that leads to local cell death and can also have systemic effects


(Year Posted:UI  410)

 

Key Code: B

Use the answer choices below to match the organism to the disease process described

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

 

__D__ Enters the subepithelial tissues in the genital or rectal area through inapparent breaks in the skin, multiplies locally, induces formation of a hard-based, painless, ulcerated genital or rectal lesion, and, simultaneously, disseminates to local lymph nodes, the blood stream and other body sites
__E__ Overgrowth of these bacteria and other anaerobes in the vagina inhibits acid-producing lactobacilli, induces vaginosis, and a thin discharge containing clue cells
__B__ Initial infection of the cervix may lead to pelvic inflammatory disease in women
__C__ Infection in the genital area results in the formation of a soft, ragged ulcer on the genitalia, small Gram-negative coccobacilli can be seen in Gram stained samples from the lesions


(Year Posted:UI  411)

 

Key Code: B

Choose the organism from the list below that is MOST LIKELY to be responsible for the disease description in question

A) Brucella abortus
B) Borrelia burgdorferi
C) Rickettsia prowazekii
D) Coxiella burnetii
E) Borrelia recurrentis
F) Treponema pallidum
G) Francisella tularensis
H) Yersinia pestis

 

__F__ A 19-year-old woman presents with a maculopapular rash on her trunk, palms, and the soles of her feet. On physical exam, her lymph nodes are found to be enlarged but not tender. Some warty, apparently painless, erosions are also observed on her perineum. Serum from the patient causes flocculation of cardiolipin
__A__ A 50 year old man reports weight loss accompanied by sporadic fever and night sweats of 6 months duration. On history, the patient reveals that he had worked in a meat processing plant the previous year. Blood culture taken during an episode of shaking chills yields a small Gram negative rod
__B__ A 10-year-old child from suburban New York develops fever, muscle and joint aches, and an annular lesion with a raised red border and an area of central clearing on his thigh. On history, the child recalls that he got a bite from a tick while playing in his wooded backyard
__C__ A reporter for the New York Times develops a severe febrile illness shortly upon return from covering a story about civil war in Burundi and Rwanda. Soon after a maculopapular rash begins on the trunk and spreads outward to the extremities
__G__ A woman and her husband return from a rabbit-hunting trip. Four days later, she develops a black eschar at the site of a small cut she suffered while skinning a rabbit. By the next day she is feverish and reports headache, malaise and pain near the infected cut
__D__ A veterinarian develops fever, malaise and a dry hacking cough 2 weeks after aiding a local farmer with a complicated delivery in a pregnant sheep from his herd. Chest X-ray is most reminiscent of an interstitial pneumonia


(Year Posted:UI  412)

 

Key Code: B

Refer to the case history below to answer questions

A man presents to the emergency room with high fever and malaise. He claims to have felt this way for about three days, worse every day. He appears underweight and very ill. Physical examination reveals needle marks in both antecubial fossae. Listening for heart sounds, you hear a distinctive systolic heart murmur. You order blood cultures and make a presumptive diagnosis of acute bacterial endocarditis. Cultures confirm your initial diagnosis and the patient begins to respond to the drug regimen you ordered

Which of the following antibiotics has the HIGHEST likelihood to be effective in this case?

A) nafcillin
B) methicillin
C) streptomycin
D) penicillin
E) vancomycin
F) gentamicin
G) rifampin


Answer: E

Which of the following virulence factors is known to be encoded by this organism?

A) protein M
B) protein capsule
C) polysaccharide capsule
D) protein A
E) exotoxin A
F) IgA protease


Answer: D

Which of the following infections would MOST commonly be associated with the same organism that caused the man's infection?

A) community-acquired bacterial pneumonia
B) bacterial meningitis
C) urinary tract infection
D) toxic shock syndrome
E) erysipelas


Answer: D

(Year Posted: 2001 UI  413)

 

Key Code: B

The lesion associated with Helicobacter pylori infection is best described as a (an)

A) abscess
B) easchar
C) pseudomembrane
D) plaque
E) ulcer


Answer: E

(Year Posted:UI  414)

 

Key Code: B

Septicemia can rapidly lead to septic shock and death. Many of the symptoms associated with septicemia and subsequent shock related to Gram-negative infection can be attributed to endotoxin's stimulation of

A) complement and GCSF
B) iron-binding protein
C) immunoglobulin production
D) IL1 and TNF
E) IL2


Answer: D

(Year Posted:UI  415)

 

Key Code: B

Which of the following pairs of arthropod vector and disease is correct?

A) body louse - tularemia
B) mosquito - plague
C) mite - Rocky Mountain spotted fever
D) deer fly - Lyme disease
E) body louse - epidemic relapsing fever


Answer: E

(Year Posted:UI  416)

 

Key Code: B

Several pathogens may be transmitted either during gestation or birth. Which of the following bacteria is MOST likely to be transmitted at this time?

A) Streptococcus pneumoniae
B) Legionella pneumophila
C) Streptococcus agalactiae
D) Hemophilus influenzae
E) Bordetella pertussis


Answer: C

(Year Posted:UI  417)

 

Key Code: B

Which of the following is a facultative intracellular pathogen?

A) Listeria monocytogenes
B) Neisseria meningitidis
C) Streptococcus pyogenes
D) Vibrio cholerae
E) Staphylococcus aureus


Answer: A

(Year Posted:UI  418)

 

Key Code: B

A 10-year-old child recovers from a Strep throat, but 3 weeks later develops a febrile illness and is brought to her pediatrician. The doctor detects a systolic heart murmur indicative of mitral valve damage. The MOST LIKELY reason that this has occurred is due to

A) S. aureus colonization of heart valve tissue causing acute bacterial endocarditis
B) S. viridans colonization of a malformed heart valve causing subacute bacterial endocarditis
C) S. pneumoniae bacteremia and effects of pneumolysin on heart tissue
D) S. pyogenes infection and development of cross reacting antibodies to heart tissue
E) S. saprophyticus urinary tract infection and the effects of renal insufficiency on heart function


Answer: D

(Year Posted:UI  419)

 

Key Code: B

A positive ppd test indicates

A) no immunity to Mycobacterium tuberculosis
B) prior exposure to M. tuberculosis
C) active primary tuberculosis
D) active infection with any of a number of mycobacterial species
E) active M. leprae infection


Answer: B

(Year Posted:UI  420)

 

Key Code: B

A 12-year-old child develops a severe diarrheal illness. The only recollection the parent has of the child eating something that no one else in the family ate was a fast food hamburger three days ago. The child appears weak and unresponsive, has a fever and a purulent bloody diarrhea. Having seen a similar case recently you are immediately concerned that a lack of quick action could rapidly lead to the development of kidney failure followed by multi-system failure. You most suspect infection with

A) ETEC
B) EHEC
C) EAEC
D) EPEC
E) Vibrio cholerae
F) Shigella dysenteriae
G) Salmonella typhi


Answer: B

(Year Posted:UI  421)

 

Key Code: B

The normal flora of the throat normally DOES NOT include moderate numbers of which of the following bacteria?

A) alpha-hemolytic streptococci
B) alpha-hemolytic pneumococci
C) beta-hemolytic streptococci
D) beta-hemolytic staphylococci
E) Gram-negative diplococci


Answer: C

(Year Posted:UI  422)

 

Key Code: B

A 72-year-old man develops a severe bacterial pneumonia due to S. pneumonia infection. He is treated with a cephalosporin and subsequently recovers. Six months later he is again hospitalized for a  S.  pneumonia infection. The antibody that he produced against the first infection was not protective against the second infection because

A) the antibody is only against the pneumococcal C substance
B) antibody levels only persist for a few weeks
C) the polysaccharide capsule of the organism is not immunogenic
D) antibodies to the greater than 80 different capsular types do not cross-protect
E) antibody to the capsule is not protective


Answer: D

(Year Posted:UI  423)

 

Key Code: B

The causative agents of which of the following diseases never enter the body in the form of an endospore?

A) tetanus
B) anthrax
C) diphtheria
D) gas gangrene
E) pseudomembranous colitis
F) enterocolitis


Answer: C

(Year Posted:UI  424)

 

Key Code: B

Humans most often acquire Salmonella typhimurium infections by

A) contact with other infected humans
B) ingestion of contaminated food
C) contact with contaminated surfaces
D) inhalation
E) penetration of broken skin


Answer: B

(Year Posted:UI  425)

Key Code: B

Which of the following organisms can be grown on artificial culture media?

A) Rickettsia rickettsii
B) Chlamydia trachomatis
C) Campylobacter jejuni
D) Mycobacterium leprae
E) Treponema pallidum

Answer: C

(Year Posted:UI  426)

 

Key Code: B

A Gram stain of an appropriate clinical specimen would be least useful in the diagnosis of which of the following infectious diseases?

A) acute bacterial meningitis
B) streptococcal pharyngitis
C) bacterial pneumonia
D) gas gangrene
E) Neisseria gonorrhoeae urethritis in males

Answer: B

(Year Posted: 2001 UI  427)

 

Key Code: B

Refer to the case history below to answer questions

An 18-month-old infant is brought to her pediatrician's office with a 6-hour history of lethargy, refusal to walk and spots on her skin. Her parents reported that she had appeared fine the day before, but awoke moaning during the night. Physical examination revealed an acutely ill child in shock, combative, disoriented and only weakly crying. Fine petechiae with some larger ecchymotic patches were noted on her forearms and legs. The doctor promptly admitted her to the hospital, where broad spectrum antibiotics were begun. 
Lab results showed that white cell count was elevated with a predominance of neutrophils with many band forms. Blood and CNS cultures were sent for microbiological workup. Gram stain of blood revealed many Gram-negative diplococci and some neutrophils with bacteria clearly inside them. Samples were plated for culture.
As her condition diminished she was placed on respiratory support. The rash further consolidated resulting in necrotizing fasciitis of both legs. She died 36 hours after admission from massive disseminated intravascular coagulation.

In choosing media for plating the clinical specimens, which of the following media would the laboratory MOST LIKELY select?

A) Buffered charcoal yeast extract agar
B) Chocolate agar
C) Thayer-Martin agar
D) Egg yolk agar

Answer: C

The bacteria's virulence factor that is primarily responsible for the systemic symptoms described in the case history is

A) hemolysin
B) capsule
C) endotoxin
D) IgA protease
E) pili
F) exotoxin A

Answer: C

Would you expect a positive Kernig's sign and/or enhanced nuchal rigidity in this child?

A) yes, because if blood cultures are positive for this organism, CSF will always be positive as well
B) no, if massive systemic infection develops, CNS infection is spared
C) maybe or maybe not, the presence of CNS infection and systemic disease are not mutually exclusive

Answer: C

The vaccine used for prophylaxis against infection with these bacteria is 

A) currently recommended for college students, especially college freshman
B) a composite vaccine consisting of polysaccharide antigen linked to protein
C) an attenuated live cellular vaccine
D) given at 2,4, and 6 months of age with later boosters
E) a toxoid
F) A whole cell, killed vaccine

Answer: A

Close contacts of documented cases of severe infection with these bacteria are given a prophylactic antibiotic. The antibiotic most often chosen is noted for its secretion to mucus membrane, the very place it is needed to prevent colonization. This antibiotic is

A) penicillin G
B) rifampin
C) ceftriaxone
D) streptomycin
E) isoniazid

Answer: B

(Year Posted: 2001 UI  428

 

Key Code: B

Along with Mycobacterium tuberculosis, which of the following mycobacteria MOST commonly causes opportunistic disease in AIDS patients?

A) M. leprae
B) M. calmette-guerin
C) M. avium-intracellulare
D) M. kansasii
E) M. bovis

Answer: C

(Year Posted: 2001 UI  429)

 

Key Code: B

The most prevalent bacterial species in the colon of an adult is

A) a facultative anaerobe
B) an obligate aerobe
C) microaerophilic
D) an obligate anaerobe
E) a facultative aerobe

Answer: D

(Year Posted: 2001 UI  430)

 

Key Code: B

A urine culture from a 22 year old female reveals numerous Gram negative rods that are lactose positive, motile and susceptible to a number of commonly used antibiotics. Which of the following organisms is MOST likely responsible for this patient's infection?

A) Escherichia coli
B) Klebsiella pneumoniae
C) Proteus mirabilis
D) Enterococcus faecalis
E) Enterobacter aerogenes

Answer: A

With regard to the infection in the 22 year old patient above. Which of the following is MOST important in the ability of this organism to cause urinary tract infections?

A) production of a potent urease
B) adherence to epithelial cells
C) resistance to antibiotics
D) ability to survive basic pH
E) production of IgA protease

Answer: B

(Year Posted: 2001 UI  431)

 

Key Code: B

Refer to the case history below to answer questions

A 3-month old infant was brought to his pediatrician after turning blue from fits of coughing. His parents noted that he had been coughing for about 3 weeks. In the beginning it seemed like a minor cold, but it had gotten much worse. General physical exam was not remarkable except for a severe, persistent cough leaving the child breathless and rapidly inspiring air. WBCs were elevated with a lymphocyte predominance. The parents report that he was up to date on immunizations having just received them about 2 and a half weeks ago. Nasopharyngeal samples were taken and sent for culture. In the meantime, a presumptive diagnosis of whooping cough was made

One of the pathogenic mechanisms associated with the organism that causes this disease is

A) invasion of the bloodstream and prolonged bacteremia
B) CNS colonization
C) paralysis of respiratory cilia
D) secretion of an enterotoxin

Answer: C

What would be the most appropriate antimicrobial therapy for this infant?

A) ampicillin effective against Gram-negative rods
B) rifampin due to its efficient secretion onto mucus membrane
C) cephalosporin due to its broad range efficacy
D) no antimicrobial therapy would be helpful at this time

Answer: D

This disease is largely preventable by vaccination. Which of the following best explains the reason for the failure of the earlier vaccination to prevent this child's illness?

A) Vaccination against this disease is not part of the earliest childhood vaccines, it is given only after 18 months
B) The vaccine used was defective
C) The child was exposed and infection initiated before an active immune response via vaccination could occur
D) Early in infection, a T cell response was needed and this child could not yet make an adequate response

Answer: C

(Year Posted: 2001 UI  432)

 

Key Code: M, Key Code: B

All of the following statements about the organisms or the carrier state are correct, EXCEPT

A) Carriers are usually asymptomatic
B) Some carriers can shed viable organisms for prolonged periods
C) In some carriers, the organisms can persist even in the presence of serum antibody
D) Organisms invariably carry multiple drug-resistance plasmids
E) Is of clinical significance in college dorms and military barracks in the case of meningitis

Answer: D

(Year Posted: 2001 UI  433)

 

Key Code: M

Lysogenic conversion refers to which one of the following phenomena?

A) Excision of prophage DNA and the subsequent formation of generalized transducing particles
B) A lytic infection with the subsequent formation of generalized transducing particles
C) The addition or loss of a phenotypic trait by a bacterium following integration of viral DNA into the chromosome
D) Alteration of the target sequence following transposition
E) None of the above

Answer: C

(Year Posted: 2001 UI  434)

 

Key Code: M

All of the following bacterial structures demonstrate antigenic diversity, EXCEPT

A) Pili
B) Peptidoglycan
C) Capsules
D) O-antigen of lipopolysacharide
E) Flagella

Answer: B

(Year Posted: 2001 UI  435)

 

Key Code: M

Pseudomonas aeruginosa is readily distinguished from the Enterobacteriaceae based on which one of the following?

A) Pseudomonas aeruginosa is Gram-positive
B) The Enterobacteriacea are anaerobic
C) Pseudomonas aeruginosa is oxidase-positive
D) Pseudomonas aeruginosa is hemolytic
E) Enterobacteriaceae are straight rods

Answer: C

(Year Posted: 2001 UI  436)

 

Key Code: B

A 39-year old male campaign staffer was brought to the E.R. with fever pain, and swelling of his right hand and arm. He reported that he developed a paper cut while pushing a "chad" through a ballot card. On exam, he had a T= 104oF, BP= 80/40, P= 120. The right hand and arm were swollen, and there were hemorrhagic bullae present. Additionally, the patient had a diffuse erythroderma (diffuse skin redness). Which one of the following is the MOST LIKELY causative pathogen?

A) Staphylococcus aureus
B) Staphylococcus epidermidis
C) Neisseria meningitidis
D) Streptococcus pyogenes
E) Pseudomonas aeruginosa

Answer: D

(Year Posted: 2001 UI  437)

 

Key Code: B

All of the following statements about post-infectious syndromes are correct, EXCEPT

A) Guillain-Barré syndrome can be associated with Campylobacterial gastroenteritis
B) Reiter's syndrome may occur following salmonellosis
C) Hemolytic uremic syndrome may occur following infection with Escherichia coli 0157:H7
D) Bacillus cereus infection may cause Reiter's syndrome
E) Acute rheumatic fever can follow Group A streptococcal pharyngitis

Answer: D

(Year Posted: 2001 UI  438)

 

Key Code: B

All of the following are characteristics of a patient presenting with pulmonary tuberculosis, EXCEPT

A) A history of coming from a high TB prevalence area
B) Was transiently homeless and stayed in a shelter due to a recent job layoff
C) A cough lasting more than three weeks
D) A clear chest x-ray
E) A history of losing weight recently while taking meals in a soup kitchen

Answer: D

(Year Posted: 2001 UI  439)

 

Key Code: M, Key Code: N

Which one of the following statements about tetanus toxin is correct?

A) Interferes with the G-protein signaling pathway
B) Blocks release of neurotransmitters (acetylcholine) in peripheral nerves
C) Cleaves proteins involved in exocytosis
D) Used to treat dystonias (excessive muscle contractions)
E) Can be found in spores that contaminate food

Answer: C

(Year Posted: 2001 UI  440)

 

Key Code: B

Which one of the following is the single most important action that one can take to protect themselves and their patients from infection?

A) Hand-washing
B) Obtaining cultures
C) Use of appropriate antibiotics
D) Isolation of the patient
E) Wearing multiple layers of gloves

Answer: A

(Year Posted: 2001 UI  441)

 

Key Code: B

Which one of the following is the most common identifiable causative agent of community acquired pneumonia?

A) Legionella pneumophilia
B) Staphylococcus aureus
C) Haemophilus influenzae
D) Streptococcus pneumoniae
E) Escherichia coli

Answer: D

(Year Posted: 2001 UI  442)

 

Key Code: B

The vertical transmission rate in an untreated, pregnant woman with late latent syphilis is approximately

A) 0%
B) 10%
C) 40%
D) 90%
E) 100%

Answer: B

(Year Posted: 2001 UI  443)

 

Key Code: M, Key Code: B

All of the following statements concerning Mycobacterium intracellulare-avium (MAI) or the disease it causes are correct, EXCEPT

A) In the HIV+ patient, infections are usually associated with gastrointestinal spread and dissemination
B) Is acquired from an environmental source
C) Is treated with the same drugs that are used for treating M. tuberculosis infections
D) Is acid-fast
E) Infection with this organism was relatively rare until the AIDS epidemic

Answer: C

(Year Posted: 2001 UI  444)

 

Key Code: M, Key Code: B

All of the following statements concerning the endogenous (normal) microbiota are correct, EXCEPT

A) Composed of multiple microorganisms, including bacteria, viruses and, fungi
B) Can elicit an immune response which does not usually result in their removal
C) Reflects the array of organisms carried by the primary care provider of the neonate
D) Cannot cause disease in their host
E) Compete with potentially pathogenic organisms thereby preventing their colonization

Answer: D

(Year Posted: 2001 UI  445)

 

Key Code: B

Which one of the following statements concerning ehrlichiosis is CORRECT?

A) The disease is usually spread by aerosals in humans
B) Emergence of the disease is attributed in part to an increased tick population
C) During infection the organism replicates extracellularly in the lung
D) Cannot be diagnosed by molecular techniques such as PCR
E) None of the above

Answer: B

(Year Posted: 2001 UI  446)

 

Key Code: M

Staphylococcus aureus and Streptococcus pyogenes have all of the following determinants of pathogenesis in common, EXCEPT

A) Enterotoxins
B) Fibrinolysin
C) Immunoglobulin-binding proteins
D) Superantigens
E) Capsule

Answer: A

(Year Posted: 2001 UI  447)

 

Key Code: M, Key Code: N

A 24-year old sexually-active female presents with dysuria (pain on urination) as well as cervical discharge. Gram stain of the cervical discharge reveals Gram-negative diplococci in pairs. Which one of the following would be the most appropriate therapy to initiate?

A) Penicillin
B) Erythromycin
C) Ceftriaxone
D) Ceftriaxone + Doxycycline
E) Ampicillin

Answer: D

(Year Posted: 2001 UI  448)

 

Key Code: M

All of the following statements concerning Rickettsia rickettsiae are correct, EXCEPT?

A) Obligate intracellular bacterium
B) Generally causes a rash in infected individuals
C) Is phagocytized by endothelial cells
D) Transmitted transovarially by infected ticks
E) Most infections caused by this organism are found in the west and southwest USA

Answer: E

(Year Posted:UI  449)

 

Key Code: B, Key Code: N

A 25-year-old women presents on a Monday morning after having spent the weekend camping. She asks to have a tick removed that became affixed to her lower leg during a long hike the day before. Which one of the following is the MOST appropriate treatment after removing the tick?

A) Cefuroxime axetil
B) Doxycycline
C) Amoxicillin
D) Any of the above would be effective
E) None of the above

Answer: E

(Year Posted:UI  450)

Key Code: B

Of the microorganisms listed below, which one is LEAST likely to cause nosocomial pneumonia?

A) Haemophilus influenzae
B) Pseudomonas aeruginosa
C) Enterobacter cloacae
D) Staphylococcus aureus
E) None of the above

Answer: A

(Year Posted:UI  451)

 

Key Code: B

Which one of the following types of nosocomial infection is associated with the highest rate of mortality?

A) respiratory tract
B) surgical Site
C) bloodstream
D) urinary Tract
E) upper respiratory tract

Answer: C

(Year Posted: 2001 UI  452)

 

Key Code: M, Key Code: N

All of the following statements about the binding of toxins to cells are correct, EXCEPT

A) A toxin can bind to all cells but the cells damaged by the toxin are those in the area where the toxin is released
B) Toxins which enter cells utilize pathways for molecules normally taken up by cells
C) Some toxins bind to carbohydrates on glycoproteins or glycolipids on the cell surface
D) The streptolysins, which produce the visible clearing on blood agar plates, act at the cell surface to damage the cell
E) The B component of the cholera toxin binds to the cell surface promoting uptake of the toxin

Answer: A

(Year Posted: 2001 UI  453)

 

Key Code: B

Refer to the case history below to answer questions

Mr. R.P. came to his doctor complaining of left leg pain, redness, tenderness and swelling which had worsened over the past 5 days since he was first seen. At that time his left thigh had become swollen and tender. The doctor noted the skin of his left heel was cracked and he had an exfoliative tinea pedis. At that time the anti-fungal clotrimazole cream was prescribed.
Examination revealed a swollen tender thigh with an erythematous rash. Temperature was slightly elevated. Blood cultures showed elevated WBC with predominance of PMNs. Mr. R.P. was admitted to the hospital. Mr. R.P. developed spiking high fevers (103oF), the erythematous rash began to rapidly spread over this thigh toward his knee and calf. WBCs increased to 20000 with many more band forms. A needle aspirate from the leading edge of the rash was submitted for microbiological workup

The bacteria responsible for Mr. R.P.'s symptoms make a variety of spreading factors which aid in the ability to cause such severe fasciitis. Which of the following is an example of such a factor?

A) siderophore
B) hyaluronidase
C) endotoxin
D) pili
E) lipoteichoic acid

Answer: B

Which of the following is the best antibiotic to prescribe for Mr. R.P.'s infection?

A) ceftriaxone
B) carbapenem
C) penicillin
D) ciprofloxacin
E) rifampin
F) vancomycin

Answer: C

Which of the following toxins' mechanism of action is MOST CLOSELY related to that which is responsible for many of Mr. R.P.'s systemic system?

A) TSST-1
B) Exotoxin A
C) Endotoxin
D) Pertussis toxin
E) Tetanospasmi

Answer: A

Mr. R.P. will make an immune response to these bacteria which will help his body to clear the infection and to heal. To which of the following bacterial components is protective antibody known to be directed?

A) M protein
B) Protein A
C) Capsule polysaccharide
D) Toxin A

Answer: A

(Year Posted: 2001 UI  454)

 

Key Code: B

Refer to the case history below to answer questions

A one-year-old boy is brought to his pediatrician with a severely inflamed cut on his knee. He has had four ear infections in the past year, and several additional wound infections that generally respond to topical therapy. Culture of the current wound reveals Gram-positive cocci that are catalase-positive and coagulase-positive.

Protein A, a purported virulence factor for these bacteria

A) is required for attachment to epithelial tissue
B) is a proteinaceous capsule
C) binds the Fc portion of immunoglobulins
D) lyses host cells resulting in tissue damage
E) is an exoenzyme that aids in spreading of bacteria through tissue

Answer: C

Given the history, which of the following immune abnormalities would be MOST LIKELY?

A) B cell deficiency
B) T cell deficiency
C) Complement deficiency
D) Eosinophil deficiency

Answer: A

Scalded skin syndrome may develop in this child. Which of the following statements presents the MOST LIKELY reason why this may not occur?

A) The bacterial strain causing this infection does not make the exfoliative toxin
B) The bacteria causing this infection are not the correct species to cause this disease
C) Underlying disease in this child will prevent the expression of the syndrome
D) Development of the syndrome requires infection of a pre-existing burn, not just a cut

Answer: A

(Year Posted: 2001 UI  455)

 

Key Code: B, Key Code: N

All of the following statements about Mycobacterium leprae infection are correct, EXCEPT

A) Is spread from person to person by inhalation or by contact
B) Leprosy is seen in California, Texas, and Hawaii in the United States
C) May occur in the tuberculoid form, with strong cell-mediated immunity, or the lepromatous form, with a strong antibody response, and poor cell-mediated immunity
D) The tuberculoid form of the disease is characterized by disfiguring skin lesions of the face and extremities
E) Leprosy is treatable, but usually has to be treated for at least two years with combinations of dapsone, rifampin, and clofazamine or ethionamide

Answer: D

(Year Posted: 2001 UI  456)

 

Key Code: B, Key Code: N

Which one of the following is indicated in the management of a 30-year old sexually-active female that presents with urgency and frequency?

A) Obtain a urine analysis and if it reveals pyuria, begin treatment with Bactrim
B) Obtain a urine analysis and culture. If the culture grows <10,000 CFU/ml, begin treatment with Vancomycin
C) Perform a urological work-up and look for renal calculi
D) Treat her sexual partner(s) to decrease the risk of subsequent urinary tract infections
E) Do nothing at this time

Answer: A

(Year Posted: 2001 UI  457)

 

Key Code: B, Key Code: N

Which one of the following is at risk for endogenous infection?

A) An HIV-negative, injection drug user
B) A patient receiving an autologous bone marrow transplant following high dose chemotherapy for breast cancer
C) An individual who enters the hospital for elective surgery
D) A patient who has been given broad spectrum antibiotics before undergoing bowel surgery
E) All of the above are at risk

Answer: E

(Year Posted: 2001 UI  458)

 

Key Code: M

Which one of the following is usually not plasmid-encoded?

A) Antibiotic resistance
B) Amino acid biosynthetic pathways
C) Catabolic enzymes for unusual substrates
D) Toxin specification
E) Heavy-metal resistance

Answer: B

(Year Posted: 2001 UI  459)

 

Key Code: B

Invasion of the colonic mucosa and the ensuing inflammatory response results in the bloody diarrhea associated with infections caused by which of the organisms listed below?

A) Enterohemorrhagic Escherichia coli and Campylobacter jejuni
B) Shigella dysenteriae, Yersinia enterocolitica and Salmonella typhi
C) Shigella dysenteriae and enterohemorrhagic Escherichia coli
D) Enteropathogenic Escherichia coli
E) Vibrio cholerae

Answer: B

(Year Posted: 2001 UI  460)

 

Key Code: B

A frantic mother brings her 6-year-old son into your office for evaluation of fever, migratory joint swelling, and jerking movements of his arms. The mother reports that her son had a sore throat 1 month ago and now has developed fevers to T = 102oF. On exam he has a T = 101oF with normal BP and pulse. His heart exam reveals a new mitral regurgitant murmur, and there is swelling and tenderness of the right knee. Skin exam reveals subcutaneous nodules of the upper extremities. Which one of the following is the MOST LIKELY diagnosis?

A) Toxic Shock syndrome
B) Acute Rheumatic Fever
C) Scarlet Fever
D) Puerperal Fever
E) Erysipilis

Answer: B

(Year Posted: 2001 UI  461)

 

Key Code: B

All of the following are important in the strategy for control/elimination of tuberculosis in the United States,
EXCEPT

A) Vigorous case finding, treatment, and, when appropriate, isolation of patients with active TB disease
B) Aggressive skin testing of all children in public schools, school teachers, and offering treatment of latent infection in all those in whom a positive skin test is found
C) Targeted skin testing of those already infected (with latent TB infection), and offering treatment to those at highest risk of developing disease, such as recent close contacts of active cases, and those with HIV, etc
D) Development of a more potent vaccine or vaccines to prevent infection
E) None of the above

Answer: B

(Year Posted: 2001 UI  462)

 

Key Code: M, Key Code: N

All of the following statements about diphtheria toxin are correct, EXCEPT

A) It is a protein
B) It is secreted by a species of Corynebacterium
C) Pseudomonas aeruginosa exotoxin A has a similar mode of action
D) Inhibits protein synthesis by inactiving the 60S ribosomal RNA subunit
E) Shiga-like toxin of Escherichia coli has a different mode of action

Answer: D

(Year Posted: 2001 UI  463)

 

Key Code: B

Which one of the following should be done to decrease the risk of a nosocomial bloodstream infection when inserting a central line?

A) Use a single or double lumen catheter whenever possible
B) The subclavian vein rather than the femoral vein whenever possible
C) Drape the patient from head to toe
D) Use of sterile gown, gloves, and mask by the practitioner
E) All of the above

Answer: E

(Year Posted: 2001 UI  464)

 

Key Code: B

All of the following rashes are commonly observed in secondary syphilis, EXCEPT

A) Follicular
B) Papulosquamous
C) Vesicular
D) Macular
E) Pustular

Answer: C

(Year Posted: 2001 UI  465)

 

Key Code: B, Key Code: N

Which one of the following statements concerning Rocky Mountain Spotted Fever is CORRECT?

A) Caused by Rickettsia rickettsiae
B) Transmitted by infected ticks feeding on a susceptible host
C) Caused by a bacterium associated with contaminated water
D) Treated with penicillin
E) A and B

Answer: E

(Year Posted: 2001 UI  466)

 

Key Code: B, Key Code: N

All of the following statements concerning anaerobic infections are correct, EXCEPT

A) Bacteroides spp. are the organisms most frequently recovered from intra-abdominal abscesses
B) Anaerobic infections can be ruled out if a culture of the abscess yields only Escherichia coli and Klebsiella spp
C) Fournier's gangrene is a mixed infection caused by both anaerobic and facultative anaerobic bacteria
D) Clindamycin is the drug of choice for anaerobic infections above the diaphragm and metronidazole is the drug of choice for aerobic infections below the diaphragm
E) A and C

Answer: B

(Year Posted: 2001 UI  467)

 

Key Code: B

All of the following statements about virulence of microorganisms are correct, EXCEPT

A) Defined as the organism's relative capacity to cause disease
B) A stable property of the organism that cannot be modified
C) May be associated with the organism's ability to enter host tissue
D) Can be neutralized by specific antibodies against a component of the organism
E) May be associated with the organism's ability to produce toxin(s)

Answer: B

(Year Posted: 2001 UI  468)

 

Key Code: M, Key Code: B, Key Code: N

Tolerance of Streptococcus pneumoniae to an antibiotic can occur as a result of which one of the following mechanisms?

A) Acquisition of a transposon
B) Induction of a new sigma factor of RNA polymerase, resulting in new gene expression
C) Mutation to the regulatory pathway that controls gene products required for autolysis
D) Activation of the general recombination system
E) None of the above

Answer: C

(Year Posted: 2001 UI  469)

 

Key Code: M

All of the following statements concerning the classification of streptococci are correct, EXCEPT

A) Streptococcus pneumoniae are alpha-hemolytic and can be serologically-typed on the basis of their polysaccharide capsules
B) Enterococci belong to Lancefield group D and can be classified by their ability to grow in 6.5% sodium chloride
C) Pneumococci and commensal viridans streptococci are both alpha-hemolytic but can be differentiated by the bile solubility test or susceptibility to optochin
D) Viridans streptococci are identified by Lancefield grouping which is based on the C polysaccharide in the cell wall
E) Streptococcus pyogenes can be differentiated from other Lancefield groups by its susceptibility to bacitracin

Answer: D

(Year Posted: 2001 UI  470)

 

Key Code: B

Which one of the following microaerophilic, spiral-shaped bacteria is responsible for a bloody diarrhea in young adult males at a rate 3-times greater than in females of the same age?

A) Helicobacter pylori
B) Klebsiella pneumoniae
C) Enterobacter aerogenes
D) Campylobacter jejuni
E) Escherichia coli

Answer: D

(Year Posted: 2001 UI  471)

 

Key Code: B, Key Code: N

A hunter in Connecticut diagnosed with Lyme disease develops a first-degree AV block with a PR interval of 0.45 seconds. Which one of the following is the recommended therapy?

A) Doxycyclin
B) Benzathine penicillin
C) Cefuroxime axetil
D) Ceftriaxone
E) Penicillin G

Answer: D

(Year Posted: 2001 UI  472)

 

Key Code: B

Which one of the following statements about Corynebacterium diphtheriae or the disease that it causes is CORRECT?

A) The organism that causes the disease is a Gram-negative spirochete
B) The organism is easily recovered from the blood during systemic disease
C) Symptoms are exclusively associated with exotoxin production
D) Most cases are acquired by droplet infection
E) C and D

Answer: E

(Year Posted: 2001 UI  473)

 

Key Code: M, Key Code: B

Which of the following statements concerning Haemophilus influenzae or the disease it causes is CORRECT?

A) Sinusitis and otitis media are most often caused by Type b encapsulated Haemophilus influenzae
B) All Haemophilus influenzae infections can now be prevented by vaccination
C) Haemophilus influenzae grows best on blood agar plates
D) Among the different serotypes, Type b is the most common cause of invasive disease
E) Haemophilus influenzae requires only the X factor for growth

Answer: D

(Year Posted:UI  474)

 

Key Code: M, Key Code: N

All of the following statements concerning peptidoglycan are correct, EXCEPT

A) It has a backbone consisting of alternating units of N-acetylmuramic acid and N-acetylglucosamine
B) It is cross-linked in three dimensions in the Gram-negative cell wall
C) Cross-links between the tetrapeptides involve D-alanine
D) It is thicker in Gram-positive than in Gram-negative cell walls
E) It can be degraded by lysozyme

Answer: B

(Year Posted:UI  475)

Key Code: B

Infections with Salmonella typhi are of greater clinical concern than with other Salmonella species because Salmonella typhi

A) Produces multiple necrotizing toxins
B) Produces a systemic, multi-organ infection
C) Can cause necrosis, hemorrhage and perforation of the intestinal wal
D) A, B and C
E) B and C

Answer: E

(Year Posted:UI  476)

 

Key Code: B

Which one of the following statements concerning Leptospira interrogans or the disease it causes is CORRECT?

A) Is a spirochete
B) Causes a zoonotic infection
C) In the primary stage, patients often have an influenza-like illness
D) Can present as an aseptic meningitis
E) All of the above

Answer: E

(Year Posted: 2001 UI  477)

 

Key Code: B

All of the following statements concerning gonococcal infections are correct, EXCEPT

A) Sexual contacts of patients with gonococcal infections should receive IM ceftriaxone only if they are symptomatic
B) Patients deficient in late complement components are at increased risk for  disseminated gonococcal infections
C) Symptomatic urogenital, oropharyngeal or anorectal disease are not usually present with disseminated gonococcal infections
D) Patients with gonococcal urethritis or cervicitis should be treated for chlamydial infections
E) None of the above

Answer: A

(Year Posted: 2001 UI  478)

 

Key Code: M, Key Code: N

Which one of the following statements concerning recombination in the recipient cell following introduction of a fragment of the bacterial chromosome by transformation is CORRECT?

A) Is additive, i.e. the chromosome of the recipient cell increases in size
B) Requires extensive homology between the two recombining DNAs
C) Is an example of site specific recombination
D) A and B
E) B and C

Answer: B

(Year Posted: 2001 UI  479)

 

Key Code: B

All of the following statements concerning neonatal sepsis caused by Streptococcus agalactiae (GBS) are correct, EXCEPT

A) Early onset disease can follow vertical transmission of the bacterium from mother to neonate
B) Late onset disease can result either from vertical or horizontal transmission of the bacterium to the neonate
C) Strains producing the serotype III capsule are most invasive
D) The incidence of early onset disease is much greater in women with heavy vaginal carriage of GBS than in women with light vaginal carriage of GBS
E) Bacteremia and pneumonia also may be consequences of neonatal sepsis

Answer: D

(Year Posted: 2001 UI  480)

 

Key Code: B, Key Code: M

The majority of cystic fibrosis patients suffer chronic infections with an encapsulated mucoid form of which one of the following organisms?

A) Klebsiella pneumoniae
B) Escherichia coli
C) Proteus mirabilis
D) Serratia marcesens
E) Pseudomonas aeruginosa

Answer: E

(Year Posted: 2001 UI  481)

 

Key Code: I, Key Code: B

Which one of the following statements about the PPD skin test is CORRECT?

A) Is specific for Mycobacterium tuberculosis
B) Can be positive in an individual who was previously immunized with BCG
C) Does not distinguish a present or past infection of tuberculosis
D) Can vary in the extent of induration so that a positive test depends upon the underlying immune status of the patient tested
E) B, C and D

Answer: E

(Year Posted: 2001 UI  482)

 

Key Code: B

All of the following statements concerning the agents that cause food or water-borne infections are correct, EXCEPT

A) Shigellosis is associated with lower abdominal cramps and tenesmus with pus and blood in the stool
B) Chronic carriage rate of 1% may occur with Shigella infection
C) Patients with sickle cell disease or decreased gastric acidity are at increased risk of infection with Salmonella spp
D) Reiter's syndrome may follow a Shigella infection
E) Disease can result from infection with very low numbers of Shigella (e.g., approximately 200 CFU)

Answer: B

(Year Posted: 2001 UI  483)

 

Key Code: M

All of the following statements concerning plasmids are correct, EXCEPT

A) A plasmid can be maintained in a cell in multiple copies
B) Plasmids do not coexist in the same cell with members of the same incompatibility group
C) Are essential for cell survival under normal environmental conditions
D) Are usually extra-chromosomal and capable of autonomous replication
E) None of the above

Answer: C

(Year Posted: 2001 UI  484)

 

Key Code: B

All of the following statements concerning clostridia are correct, EXCEPT

A) Pathogenic clostridia are found both in the soil and as part of the normal microbiota of the colon
B) Antibiotic-associated (pseudomembranous colitis) is due to toxins produced by Clostridium difficile
C) Anaerobic conditions at the wound site are required to cause tetanus, by allowing the bacterium to sporulate and form tetansospasmin
D) Botulism can result from infection of the umbilical stump
E) Food poisoning caused by Clostridium perfringens requires the ingestion of a large number (106-107) of vegetative cells

Answer: C

(Year Posted: 2001 UI  485)

 

Key Code: M

All of the following statements concerning bacterial spores are correct, EXCEPT

A) They are formed by some Gram-positive but never by Gram-negative bacteria
B) They are highly resistant to many physical and chemical agents
C) They form when spore-forming bacteria enter the stationary phase of growth
D) The location of the spore is a characteristic of the particular bacterial species
E) Their ability to survive is based on their enhanced metabolic activity

Answer: E

(Year Posted: 2001 UI  486)

 

Key Code: B, Key Code: N

All of the following are features of Clostridium difficile or the disease it causes, EXCEPT

A) Causes a pseudomembranous colitis
B) Associated with the use of b-lactam antibiotics and clindamycin
C) Incidence of the disease is far greater following the use of parenteral antibiotics
D) Source of the organism may be exogenous or endogenous
E) Cause by an enterotoxin (toxin A) and a cytotoxin (toxin B)

Answer: C

(Year Posted: 2001 UI  487)

 

Key Code: M, Key Code: B

Which one of the following statements concerning Lancefield group C, F, and G streptococci is CORRECT?

A) Members of the normal pharyngeal, gastrointestinal and genitourinary microbiota
B) Some produce large zones of beta-hemolysis similar to Streptococcus pyogenes
C) Acute glomerulonephritis may follow pharyngeal infection
D) A and B
E) A, B and C

Answer: E

(Year Posted: 2001 UI  488)

 

Key Code: B, Key Code: M, Key Code: N

The similar clinical presentation of cholera and enterotoxigenic Escherichia coli (ETEC) infections is due to which one of the following?

A) Identical mechanism of action of cholera toxin and LT toxin
B) Identical mechanism of action of cholera toxin and ST toxin
C) Ability of CTX phage to infect both species
D) Synthesis of TCP pili by Escherichia coli
E) Co-habitation of the estuarine environment by these bacteria

Answer: A

(Year Posted: 2001 UI  489)

 

Key Code: B, Key Code: I

A 26-year old male medical student is referred to you for evaluation. He reports that he has had two bouts of meningococcal meningitis, and 3 bouts of gonorrhea. The cause of these recurrent infections could best be explained by which one of the following?

A) Selective IgA deficiency
B) Terminal complement deficiency
C) Neutrophil deficiency
D) CD4 T-cell deficiency
E) Chronic fatigue syndrome

Answer: B

(Year Posted: 2001 UI  490)

 

Key Code: B

Which one of the following pairs of organisms represent the MOST common bacterial causes of cystitis in an otherwise healthy woman?

A) Escherichia coli and Proteus mirabilis
B) Escherichia coli and Staphylococcus saprophyticus
C) Escherichia coli and Klebsiella oxytoca
D) Escherichia coli and Pseudomonas aeruginosa
E) Enterococcus faecalis and Staphylococcus saprophyticus

Answer: B

(Year Posted: 2001 UI  491)

 

Key Code: M, Key Code: N

By definition, a missense mutation

A) Always changes a codon encoding an amino acid to a stop codon
B) May result in a frameshift
C) May cause substitution of one amino acid for another in the gene product
D) Stimulates the binding of f-met tRNA
E) None of the above

Answer: C

(Year Posted: 2001 UI  492)

 

Key Code: M

All of the following statements concerning the surface structure of bacteria are correct, EXCEPT

A) Flagella are antigenically-invariable
B) Polysaccharide capsules inhibit phagocytosis
C) The Lipid A portion of lipopolysaccharide is responsible for its toxicity
D) Common pili mediate the adherence of bacteria to mucosal epithelium
E) Lipoteichoic may function as an adhesin for some Gram-positive bacteria

Answer: A

(Year Posted: 2001 UI  493)

 

Key Code: M, Key Code: B, Key Code: N

All of the following statements concerning Bacteroides fragilis are correct, EXCEPT

A) It is a Gram-negative rod that is part of the endogenous microbiota of the large bowel
B) It is capable of causing disease as a result of mono-infection
C) The capsule contributes to its pathogenesis
D) Produces a b-lactamase
E) Vancomycin-Kanamycin blood agar is useful in isolating the organism from clinical specimens

Answer: B

(Year Posted: 2001 UI  494)

 

Key Code: M, Key Code: B

A culture of skin lesions from a patient with pyoderma (impetigo) shows numerous colonies surrounded by a zone of beta-hemolysis on a blood agar plate. A Gram-stained smear shows Gram-positive cocci. A catalase test of a beta-hemolytic colony is negative. Which one of the following bacteria is the MOST likely cause?

A) Streptococcus pyogenes
B) Staphylococcus aureus
C) Staphylococcus epidermidis
D) Staphylococcus saprophyticus
E) Streptococcus bovis

Answer: A

(Year Posted: 2001 UI  495)

 

Key Code: B

Which one of the following serogroups of Vibrio cholerae is associated with epidemic and pandemic outbreaks?

A) All of the 155 known serogroups
B) O157:H7 and 0111:NM
C) O1, biotype E1 Tor and O139 Bengal
D) Only serogroup O1
E) O6, O55, and O78

Answer: C

(Year Posted: 2001 UI  496)

 

Key Code: B

A 43-year old female presented to the E.R. with pain and swelling of her left hand. Her exam revealed cellulitis of the left hand and arm. She reported that she was preparing fresh tilapia for dinner one day ago and may have cut herself at that time. Which one of the following is the MOST LIKELY causative pathogen?

A) Streptococcus iniae
B) Staphylococcus aureus
C) Staphylococcus epidermidis
D) Enterococcus faecalis
E) Corynebacterium acnes

Answer: A

(Year Posted: 2001 UI  497)

 

Key Code: B, Key Code: M

Which one of the following statements about Brucella melitensis is CORRECT?

A) Survives as an intracellular bacterium, infecting neutrophils and other white cells
B) Causes a zoonotic infection
C) Can be transmitted via aerosols or in contaminated dairy products
D) Causes infections more often in third world countries
E) All of the above

Answer: E

(Year Posted: 2001 UI  498)

 

Key Code: B, Key Code: N

Which of the following statements concerning Chlamydia pneumoniae or the disease that it causes is CORRECT?

A) It is a major cause of pneumonia in patients with cell-mediated immunity deficiencies
B) Pharyngitis and hoarseness can occur
C) Culture is the easiest way of establishing the diagnosis
D) Can be transmitted to humans by psittacine birds
E) Penicillin is the drug of choice for treatment

Answer: B

(Year Posted:UI  499)

 

Key Code: B

All of the following statements about Bordetella pertussis are correct, EXCEPT

A) Clinical manifestations are secondary to toxin production rather than to tissue invasion
B) Fever is a common primary manifestation of the disease
C) Lymphocytosis as high as 40,000/mm3 is common
D) Humans are the only reservoir
E) Is highly communicable among infants less than one year of age

Answer: B

(Year Posted:UI  500)