Microbiology Board Exam

Which of the following is more likely to be diagnostic of an acute infection?

A total acute antibody titer of 2 followed by a convalescent titer of 16

Diagnosis of group A streptococci infection is indicated by the presence of:

Anti-DNase

The rapid plasma reagin assay for syphilis does not need to be read microscopically because the antigen is:

Complexed with charcoal

The VDRL test for syphilis is classified as a:

Flocculation reaction

One cause of a false positive VDRL test is:

Systemic lupus erythematosus

Which of the following is an example of a treponemal antigen test used for the diagnosis of syphilis?

FTA-ABS

A serum sample is positive for HBsAg. This result indicates that the person from whom the serum was taken:

Has either active or chronic hepatitis B infection

Patient serum is mixed with a suspension of guinea pig antigen. When the sample is then mixed with horse red blood cells, agglutination occurs. This is suggestive of an infection caused by:

Epstein Barr virus

The first serologic marker to appear in patients with acute hepatitis B virus infection is:

HBsAg

Why does vaccination against hepatitis B virus also prevent hepatitis D virus infections?

HDV requires the host to be concurrently infected with HBV

Anti-HAV: Nonreactive

Anti-HBc: Reactive

Anti-HBs: Nonreactive

HBsAg: Reactive

HBeAg: Reactive

Anti-HCV: Nonreactive

Chronic HBV infection

CMV IgG titer: 20

EBV IgM titer: 80

Acute EBV infection

What is the next step after a reactive ELISA for HIV?

Repeat the ELISA on the same sample

A test for the hydrolysis of esculin in the presence of bile is especially useful in identifying species of the genus:

Enterococcus

The organism associated with a disease characterized by the presence of a psuedomembrane in the throat and the production of exotoxin that is absorbed into the bloodstream with a lethal effect is:

Corynebacterium diphtheriae

Enterotoxin produced by Staphylococcus aureus is responsible for causing:

Enterocolitis

Abiotrophia, formerly known as nutritionally variant streptococci, will not grow on routine blood or chocolate stars because they are deficient in:

Pyridoxal/Vitamin B6

Exfoliatin produced by S. aureus is responsible for causing:

Scalded skin syndrome

S. pyogenes can be presumptively identified using a:

PYR disk

A GPC that is catalase positive, nonmotile, lysostaphin resistant and modified oxidase positive is best identified as a member of the genus:

Micrococcus

Nocardia asteroides infections in humans characteristically produce:

Draining cutaneous sinuses

Erysipelothrix infections in humans characteristically produce:

Pathology at the point of entrance of the organism

What organism can be presumptively identified by the CAMP test?

S. agalactiae

S. saprophyticus is the cause of:

Urinary tract infections

GPB with translucent beta-hemolytic colonies on SPA

Listeria monocytogenes

The etiologic agent most commonly associated with septicemia and meningitis of newborns is:

S. agalactiae

Which of the following is the most commonly isolated species of Bacillus in opportunistic infections?

B. cereus

Loeffler's serum medium is recommended for the cultivation of:

Cornyebacterium diphtheriae

On Tinsdale agar, colonies of C. diphtheriae are characterized by the observance of:

Black colonies on the culture medium surrounded by brown halos

Precipitates of diphtheria toxin and antitoxin formed in agar gels are an in vitro means for detecting toxigenic strains of C. diphtheriae. The name of this test is:

Elek test

The etiologic agent of the disease erysipelas is:

S. pyogenes

S. aureus when present could most likely be recovered from a stool sample if the primary plating medium included:

Phenylethyl alcohol

A common member of the normal flora of the upper respiratory tract is:

Viridans streptococcus

Streptococci obtain all their energy from the fermentation of sugars to:

Lactic acid

Streptococci are unable to synthesize the enzyme:

Catalase

The beta hemolysis produced by group A streptococcus seen on the surface of a sheep blood agar plate is primarily the result of:

Streptolysin S

When an infection due to streptomyces is suspected, isolates can be separated from most other bacteria by:

Incubating the culture at 25 C

The production of H2S is one characteristic used to differentiate which of the aerobic GPB?

Erysipelothrix

Test tube brush motility at room temperature

Listeria monocytogenes

A former species of Corynebacterium pathogenic for swine, horses and cattle which grows pale pink colonies.

Rhodococcus equi

Which of the following is not appropriate when describing S. pneumoniae?

Bile resistant

Nocardia can be differentiated from Actinomyces based on:

Nocardia being catalase positive

Enterococcus faecium is characteristically:

Able to grow in the presence of high concentrations of salt

A negative PYR test is demonstrated by:

Viridans streptococci

A gram stain of a sputum specimen from a patient with a suspected case of lobar pneumonia reveals many WBCs and many GPC, which are primarily diplococci. Which of the following is true?

An optochin test should be performed on the culture isolate

A child presented in August at the ped clinic with a superficial skin infection of the neck. The large, itchy lesions were cultured and the diagnosis of impetigo was made. One of the etiologic agents of this is:

S. pyogenes

An identifying characteristic of S. aureus is:

Mannitol fermentation positive

Which of the following organisms is able to hydrolyze sodium hippurate?

S. agalactiae

Which of the following is not characteristic of L. monocytogenes?

Catalase negative

Which of the following is not associated with S. aureus?

Endotoxin production

Which of the following is a characteristic of staph that would help in their isolation from clinical specimens?

High salt tolerance

Which of the Bacillus is nonmotile?

B. anthracis

Which of the following diseases involves erythrogenic toxin?

Scarlet fever

Cultures of the posterior pharynx are most commonly submitted to the clinical lab for the detection of:

S. pyogenes

S. sanguis is most commonly associated with which of the following clinical conditions?

Subacute bacterial endocarditis

Rust-colored sputum in cases of lobar pneumonia is characteristic of which of the following possible etiologic agents?

S. pneumoniae

A urine culture from a 23 yo female grew a catalase positive GPC which would most likely be:

S. saprophyticus

Cystine-tellurite blood agar plate are recommended for the isolation of:

C. diphtheriae

The pulmonary form of anthrax is known as:

Woolsorters disease

Pleomorphic GPB in a gram stain best describes:

C. pseudodiphtheriticum

An aerobic GPB known to cause bacteremia in immunocompromised patients is:

C. jeikeium

A brain abscess was detected by MRI and aspirated material grew an aerobic, branching GP organism which stains acid fast; most likely:

N. asteroides

Which of the following is catalase negative?

Leuconostoc

Colonies of L. monocytogenes on a SBA most closely resembles of:

S. agalactiae

The most common etiologic agent of infections associated with the surgical insertion of prosthetic devices:

S. epidermidis

The description of Medusa head colonies on solid agar is characteristic of:

B. anthracis

Which of the following is most likely to be isolated in cultures from the anterior nares of healthcare workers?

S. aureus

Ethylhydrocupreine HCl susceptibility is a presumptive test for the identification of:

S. pneumoniae

Solubility in the presence of sodium deoxycholate is characteristic of:

S. pneumoniae

Family members attending a picnic became ill about 2 hours after eating. The illness was characterized by rapid onset of violent vomiting. The bacteria is most likely:

S. aureus

The novobiocin susceptibility test is used for the identification of:

S. saprophyticus

Tellurite reduction is used for the presumptive identification of:

C. diphtheriae

The etiologic agent of the majority of adult joint infections is:

S. aureus

Which of the following is associated with infections in humans often linked to deli meats and improperly pasteurized dairy products?

L. monocytogenes

B. cereus has been implicated as the etiologic agent in cases of:

Food poisoning

The causative agent of malignant pustule is:

B. anthracis

An infant was hospitalized with a severe tender erythema. The child's epidermis was loose and large areas of skin could be peeled off. The condition is associated with:

S. aureus

A catalase negative GPC is isolated from a urine sample of a hospitalized patient. The bacterium produced a black pigment on bile-esculin agar and formed acid from glucose in the presence of 6.5% NaCl. What is the bacteria?

Enterococcus faecalis

In suspected cases of brucellosis, the optimal specimen to be collected for the isolation of the etiologic agent is:

Blood

The majority of isolated of Klebsiella are:

K. pneumoniae

The enterotoxins of both V. cholerae O1 and E. coli produce serious diarrhea by which mechanism?

Stimulation of adenylate cyclase which gives rise to excessive fluid secretion by the cells of the small intestine

Colonies of Neisseria turn color when a redox reagent is applied. The color change is indicative of the activity of the bacterial enzyme:

Cytochrome oxidase

Which of the following is not true of S. sonnei?

Large numbers of organisms must be ingested to produce disease

An environmental sampling study of respiratory therapy equipment produced cultures of a yellow, nonfermentative GNB which is likely:

Chryseobacterium

The characteristics of being lactose negative, citrate negative, urease negative, lysine decarboxylase negative and nonmotile:

Shigella dysenteriae

A fermentative GNB that is oxidase positive, motile and grows well on MAC:

Aeromonas hydrophilia

Fecal cultures are inoculated on TCBS agar for the isolation:

Vibrio

The K antigen of the family Enterobacteriaceae is:

Heat labile

The causative agent of melioidosis is:

Burkholderia pseudomallei

Which microbe will grow only on culture media supplemented with cystine?

Francisella tularensis

A culture of an ulcer grows a GNB, on TSI had acid/acid and gas. Citrate:negative

Indole:positive

Urease:negative

ONPG:positive

VP: negative

E. coli

An example of an oxidase positive glucose nonfermenting organism is:

P. aeruginosa

A fastidious GNB was isolated from a case of periodontal disease which upon darkfield examination has gliding motility. The bacteria is:

Capnocytophaga

The species of Vibrio closely associated with rapidly progressing wound infections seen in patients with underlying liver disease:

V. vulnificus

Severe DIC often complicates cases of septicemia caused by:

N. meningitidis

The H. flu vaccine protects against:

Serotype b

Which of the following is not characteristic of S. typhi?

Large amounts of H2S are produced in TSI agars

The STD characterized by genital ulcers and lymphadenopathy caused by GNB:

Chancroid

Which of the following is most likely to be acquired by a hot tub or whirlpool?

Pseudomonas dermatitis

Campylobacter are associated most frequently with cases of:

Gastroenteritis