question
Infection of the urinary tract is most frequently associated with:
answer
Escherichia coli
question
MacConkey media for screening suspected cases of hemorrhagic E coli 0157:H7 must contain:
answer
sorbitol
question
Members of the family Enterobacteriaceae share which one of the following characteristics?
answer
reduce nitrate to nitrite.
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Which one of the following genera is among the least biochemically reactive members of the Enterobacteriaceae?
answer
Shigella
question
Which one of the following gram negative bacilli ferments glucose
answer
Yersinia enterocolitica
question
An organism was inoculated to a TSI tube and gave the following reactions: alkaline slant/acid butt, H2S gas produced:
answer
Salmonella typhimurium
question
A TSI tube inoculated with an organism gave the following reactions: alkaline slant, acid butt, no H2S, no gas produced
answer
Shigella dysenteriae
question
Which of the following organisms can grow in the small bowel and cause diarrhea in children, traveler's diarrhea, or a severe cholera-like syndrome through the production of enterotoxins?
answer
Escherichia coli.
question
Shigella species characteristically are:
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nonmotile.
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A gram negative bacillus has been isolated from feces, and the confirmed biochemical reactions fit those of Shigella. The organism does not agglutinate in Shigella antisera. What should be done next?
answer
Boil the organism and retest with the antisera.
question
Biochemical reactions of an organism are consistent with Shigella. A suspension is tested in antiserum without resulting agglutination. However, after 15 minutes of boiling, agglutination occurs in group D antisera. The Shigella species is:
answer
sonnei
question
A 25 year old man who had recently worked as a steward on a transoceanic grain ship presented to the emergency room with high fever, diarrhea and prostration. Axillary lymph nodes were hemorrhagic and enlarged. A Wayson stain of the aspirate shoed bacilli that were bipolar, resembling safety pins. The most likely identification of this organism is:
answer
Yersinia perstis
question
Plesiomonas shigelloides is a relatively new member of the family Enterobacteriaceae. what characteristic separates it from other members of the Enterobacteriaceae?
answer
It is oxidase positive.
question
The stock cultures needed for quality control testing of motility are:
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Klebsiella pneumoniae/Escherichia coli
question
The stock cultures needed for quality control testing of oxidase production are:
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Escherichia coli/Pseudomonas aeruginosa
question
The stock cultures needed for quality control testing of deamination activity are:
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Proteus mirabilis/Escherichia coli
question
The stock cultures needed for quality control testing of deoxyribonuclease (DNase) production are:
answer
Serratia marcescens/Escherichia coli
question
Quality control of the spot indole test requires the use of ATCC cultures of:
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Escherichia coli/Enterobacter cloacae
question
An organism that exhibits the satellite phenomenon around colonies of staphylococci is:
answer
Haemophilus influenzae
question
An organism isolated from the surface of a skin burn is found to produce a diffusible green pigment on a blood agar plate. Further studies of the organism would most likely show the organism to be:
answer
Pseudomonas aeruginosa
question
A nonfermenting gram negative bacillus is isolated from a wound. The nitrate and oxidase are strongly positive. The growth on sheep blood agar has a grape like odor. The organisms is:
answer
Pseudomonas aeruginosa
question
A small, gram negative bacillus is isolated from an eye culture. It grows only on chocolate agar and is oxidase variable. The most likely organisms is:
answer
Haemophilus influenzae
question
The optimal incubator temperature for isolation of the campylobacter jejuni/coli group is:
answer
42c
question
A gastroenterologist submits a gastric biopsy from a patient with a peptic ulcer. To obtain presumptive evidence of Helicobacter pylori, a portion of the specimen should be added to which media?
answer
Urea broth
question
A 4 year old boy is admitted to the hospital with suspected meningitis. He has not had most of the childhood vaccines. The suspected pathogen is:
answer
Haemophilus influenzae
question
A gram stain of a touch prep from a gastric biopsy shows gram negative bacilli that are slender and curved. The most likely pathogen is:
answer
Helicobacter pylori
question
A cerebrospinal fluid has been inoculated onto sheep blood and chocolate agar plates and into a tube of trypticase soy broth. All media were incubated in an atmosphere of 5% CO2. Which of the following organisms would usually be isolated by this procedure?
answer
Haemophilus influenzae.
question
If present, a characteristic that is helpful in separating Pseudomonas aeruginosa from other members of the pseudomonas family is:
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Growth at 42c.
question
Which one of the following results is typical of Campylobacter jejuni:
answer
Optimal growth at 42c.
question
Optimum growth of Campylobacter jejuni is obtained on suitable media incubated at 42c in an atmosphere containing:
answer
6% O2, 10%CO2, 85-90% nitrogen
question
Haemophilus influenzae is most likely considered normal indigenous flora in the:
answer
Oropharynx
question
Haemophilus influenzae becomes resistant to ampicillin when the organism produces a:
answer
Beta-lactamase enzyme
question
An isolate on chocolate agar from a patient with epiglottitis was suggestive of Haemophilus species. Additional testing showed that the isolate required NAD for growth and was nonhemolytic. The organism is most likely Haemophilus:
answer
parainfluenzae
question
Which of the following specimens is considered to be the most sensitive for the recovery of Brucella in cases of chronic infection?
answer
bone marrow
question
While swimming in a lake near his home, a young boy cut his foot, and an infection developed. The culture grew a nonfastidious gram negative, oxidase positive, beta-hemolytic, motile bacilli that produced deoxyribonuclease. Them sot likely identification is:
answer
Aeromonas hydrophila
question
Serum samples collected from a patient with pneumonia demonstrate a rising antibody titer to Legionella. A bronchoalveolar lavage (BAL) specimen from this patient had a positive antigen test for Legionella but no organisms were recovered on buffered charcoal yeast extract medium after 2 days of incubation. The best explanation is that the:
answer
Culture was not incubated long enough.
question
Which characteristic best differentiates Acinetobacter species from Moraxella species?
answer
Production of indophenol oxidse
question
an organism has been identified as a member of the fluorescent group of Pseudomonas. Which of the following sets of tests should be used to determine the species of the organism?
answer
Growth at 42c, pyocyanin production, gelatinase production.
question
Appropriate culture requirements for a specimen from a patient suspected of having tularemia include:
answer
A media with cysteine such as buffered charcoal yeast extract agar.
question
A laboratory aid receives a bronochoscopy sample with the request for culture of Legionella. The assistant asks a microbiologist for direction on plating protocol. the correct response from the microbiologist is:
answer
culture on buffered charcoal yeast extract agar with antibiotics.
question
A community hospital microbiology laboratory is processing significant numbers of stool cultures because of an outbreak of diarrhea following heavy rains and flooding in the country. A media that should be incorporated in the plating protocol is:
answer
Thiosulfate citrate bile salts sucrose for Vibrio species.
question
Differentiating tests that will separate Burkholderia from Stenotrophomonas include:
answer
oxidase.