Microbio Flashcards by Marlo Roque

The aseptic collection of blood cultures requires that the skin be cleansed with:

A. 2% iodine and then 70% alcohol solution
B. 70% alcohol and then 2% iodine or an iodophor
C. 70% alcohol and then 95% alcohol
D. 95% alcohol only

B. 70% alcohol and then 2% iodine or an iodophor

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When cleansing the skin with alcohol and then iodine for the collection of a blood culture, the iodine (or iodophor) should remain intact on the skin for at least:

A. 10 seconds
B. 30 seconds
C. 60 seconds
D. 5 minutes

C. 60 seconds

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What is the purpose of adding 0.025% to 0.050% sodium polyanethol sulfonate (SPS) to nutrient broth media for the collection of blood cultures?

A. It inhibits phagocytosis and complement
B. It promotes formation of a blood clot
C. It enhances growth of anaerobes
D. It functions as a preservative

A. It inhibits phagocytosis and complement

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A flexible calcium alginate nasopharyngeal swab is the collection device of choice for
recovery of which organism from the nasopharynx?

A. Staphylococcus aureus
B. Streptococcus pneumoniae
C. Corynebacterium diphtheriae
D. Bacteroides fragilis

C. Corynebacterium diphtheriae

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Semisolid transport media, such as Amies, Stuart, or Cary-Blair, are suitable for the transport of swabs for culture of most pathogens except:

A. Neisseria gonorrhoeae
B. Enterobacteriaceae
C. Campylobacter fetus
D. Streptococcus pneumoniae

A. Neisseria gonorrhoeae

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Select the method of choice for recovery of anaerobic bacteria from a deep abscess.

A. Cotton fiber swab of the abscess area
B. Skin snip of the surface tissue
C. Needle aspirate after surface decontamination
D. Swab of the scalpel used for débridement

C. Needle aspirate after surface decontamination

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Select the primary and differential media of choice for recovery of most fecal pathogens.

A. MacConkey, blood, birdseed, and Campylobacter (Campy) agars
B. Hektoen, MacConkey, MacConkey-Sorbitol, Campy blood, colistin–nalidixic acid (CNA) agars; Selenite-F broth (SEL)
C. CNA and Christensen urea agars and thioglycollate media
D. Blood, Campy, Mueller-Hinton agars, and thioglycollate media

B. Hektoen, MacConkey, MacConkey-Sorbitol, Campy blood, colistin–nalidixic acid (CNA) agars; Selenite-F broth (SEL)

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Select the media of choice for recovery of Vibrio cholerae from a stool specimen.

A. MacConkey agar and thioglycollate media
B. Thiosulfate–citrate–bile–sucrose (TCBS) agar and alkaline peptone water (APW) broth
C. Blood agar and SEL broth
D. CNA agar

B. Thiosulfate–citrate–bile–sucrose (TCBS) agar and alkaline peptone water (APW) broth

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CNA agar is used primarily for the recovery of:

A. Neisseria species
B. Enterobacteriaceae
C. Pseudomonas aeruginosa
D. Staphylococcus aureus

D. Staphylococcus aureus

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In the United States, most blood agar plates are prepared with 5% or 10% red blood cells (RBCs) obtained from:

A. Sheep
B. Horses
C. Humans
D. Dogs

A. Sheep

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All of the following are appropriate when attempting to isolate N. gonorrhoeae from a genital specimen except:

A. Transport the genital swab in charcoal transport medium
B. Plate the specimen directly on modified Thayer-Martin (MTM) medium
C. Plate the specimen directly on New York City or Martin-Lewis agar
D. Culture specimens in ambient oxygen at 37°C

D. Culture specimens in ambient oxygen at 37°C

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Chocolate agar and MTM agar are used for the recovery of:

A. Haemophilus spp. and Neisseria spp., respectively
B. Haemophilus spp. and N. gonorrhoeae, respectively
C. Neisseria spp. and Streptococcus spp., respectively
D. Streptococcus spp. and Staphylococcus spp., respectively

B. Haemophilus spp. and N. gonorrhoeae, respectively

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Cycloserine–cefoxitin–fructose agar (CCFA) is used for the recovery of:

A. Yersinia enterocolitica
B. Yersinia intermedia
C. Clostridium perfringens
D. Clostridium difficile

D. Clostridium difficile

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Deoxycholate agar (DCA) is useful for the isolation of:

A. Enterobacteriaceae
B. Enterococcus spp.
C. Staphylococcus spp.
D. Neisseria spp.

A. Enterobacteriaceae

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Xylose lysine deoxycholate (XLD) agar is a highly selective medium used for the recovery of which bacteria?

A. Staphylococcus spp. from normal flora
B. Yersinia spp. that do not grow on Hektoen agar
C. Enterobacteriaceae from gastrointestinal specimens
D. Streptococcus spp. from stool cultures

C. Enterobacteriaceae from gastrointestinal specimens

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A sheep blood agar plate is used as a primary isolation medium when all of the following organisms are to be recovered from a wound specimen except:

A. β-Hemolytic streptococci and coagulase-positive staphylococci
B. Haemophilus influenzae and Haemophilus parainfluenzae
C. Proteus spp. and Escherichia coli
D. Pseudomonas spp. and Acinetobacter spp.

B. Haemophilus influenzae and Haemophilus parainfluenzae

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Prereduced and vitamin K1-supplemented blood agar plates are recommended isolation media for:

A. Mycobacterium marinum and Mycobacterium avium intracellulare
B. Bacteroides, Peptostreptococcus, and Clostridium spp.
C. Proteus spp.
D. Enterococcus spp.

B. Bacteroides, Peptostreptococcus, and Clostridium spp.

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Which procedure(s) is (are) appropriate for the diagnosis of Chlamydia spp. infections when using genital specimens?

A. Obtain urethral, cervical swabs and urine specimens placed in transport media for the direct detection of antigen or nucleic acid and/or culture
B. Plate onto blood and chocolate agar
C. Inoculate into thioglycollate (THIO) broth
D. Plate onto MTM agar within 24 hours

A. Obtain urethral, cervical swabs and urine specimens placed in

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Specimens for virus culture should be transported in media containing:

A. Antibiotics and 5% sheep blood
B. Saline and 5% sheep blood
C. 22% bovine albumin
D. Antibiotics and protein nutrient

D. Antibiotics and protein nutrient

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Cerebrospinal fluid (CSF) should be cultured immediately, but
if delayed, the specimen should be:

A. Refrigerated at 4°C to 6°C
B. Frozen at –20°C
C. Stored at room temperature for no longer than 24 hours
D. Incubated at 37°C and cultured as soon as possible

D. Incubated at 37°C and cultured as soon as possible

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The most sensitive method for the detection of β-lactamase in bacteria is by the use of:

A. Chromogenic cephalosporin
B. Penicillin
C. Oxidase
D. Chloramphenicol acetyltransferase

A. Chromogenic cephalosporin

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The breakpoint of an antimicrobial drug refers to:

A. The amount needed to cause bacteriostasis
B. A minimum inhibitory concentration (MIC) of 16 μg/mL or greater
C. An MIC of 64 μg/mL or greater
D. The optimal therapeutic level of drug that is achievable in serum

D. The optimal therapeutic level of drug that is achievable in serum

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Which of the following variables may change the results of an MIC?

A. Inoculum size
B. Incubation time
C. Growth rate of the bacteria
D. All of these options

D. All of these options

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According to the Kirby-Bauer standard antimicrobial susceptibility testing method, what should be done when.
interpreting the zone size of a motile, swarming organism, such as a Proteus species?

A. The swarming area should be ignored
B. The results of the disk diffusion method are invalid
C. The swarming area should be measured as the growth boundary
D. The isolate should be retested after diluting to a 0.05 McFarland
standard

A. The swarming area should be ignored

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25. Which class of antibiotics is used for the treatment of serious gram-negative infections as well as infections with Mycobacterium tuberculosis? A. Cephalosporins B. Penicillins C. Tetracyclines D. Aminoglycosides

D. Aminoglycosides

26. Select the medium best suited for the recovery of Y. enterocolitica from a patient with gastroenteritis. A. Hektoen agar B. Cefsulodin–irgasan–novobiocin (CIN) agar C. Blood agar D. Eosin methylene blue agar

B. Cefsulodin–irgasan–novobiocin (CIN) agar

27. A suspected case of plague requires which of the following procedures to confirm Yersinia pestis? A. Collection of multiple sets of blood culture specimens B. Incubation of blood cultures at both 28°C and 35°C C. Culture aspirates from bubos to MacConkey agar at room temperature D. All of these options

D. All of these options

28. SITUATION: Abdominal pain, fever, vomiting, and nausea prompted an older male to seek medical attention. A watery stool specimen producing no fecal leukocytes or erythrocytes was cultured, and it grew a predominance of gram-negative fermentative bacilli. The colonies were β-hemolytic on blood agar and cream colored on MacConkey agar. The colonies were both oxidase and catalase positive. What is the most likely identification? A. Aeromonas hydrophilia B. Escherichia coli C. Salmonella spp. D. Shigella spp.

A. Aeromonas hydrophilia

29. SITUATION: Several attendees of a medical conference in the Gulf coast area became ill after frequenting a seafood restaurant. A presumptive identification of V. cholerae was made after stool specimens from several subjects grew clear colonies on MacConkey agar and yellow colonies on TCBS agar. Which key tests would help eliminate Aeromonas and Plesiomonas spp.? A. Mannitol fermentation, Na+ requirement B. Oxidase, motility C. Oxidase, nitrate D. Hemolysis on blood agar, catalase

A. Mannitol fermentation, Na+ requirement

30. SITUATION: A group of elementary students became ill after eating undercooked ground beef prepared in the school cafeteria. The suspected pathogen, E. coli serotype 0157:H7, is usually recovered using which of the following media? A. Xylose lysine deoxycholate agar B. MacConkey agar C. MacConkey agar with sorbitol D. Hektoen agar

C. MacConkey agar with sorbitol

1. Biochemically, Enterobacteriaceae species are gram-negative rods that: A. Ferment glucose, reduce nitrate to nitrite, and are oxidase negative B. Ferment glucose, produce indophenol oxidase, and form gas C. Ferment lactose and reduce nitrite to nitrogen gas D. Ferment lactose and produce indophenol oxidase

A. Ferment glucose, reduce nitrate to nitrite, and are oxidase negative

2. The ortho-nitrophenyl-β-galactopyranoside (ONPG) test is most useful when differentiating: A. Salmonella spp. from Pseudomonas spp. B. Shigella spp. from some strains of Escherichia coli C. Klebsiella spp. from Enterobacter spp. D. Proteus vulgaris from Salmonella spp.

B. Shigella spp. from some strains of Escherichia coli

3. The Voges-Proskauer (VP) test detects which end product of glucose fermentation? A. Acetoin B. Nitrite C. Acetic acid D. Hydrogen sulfide

A. Acetoin

4. At which pH does the methyl red (MR) test become positive? A. 7.0 B. 6.5 C. 6.0 D. 4.5

D. 4.5

5. A positive Simmons citrate test is seen as a: A. Blue color in the medium after 24 hours of incubation at 35°C B. Red color in the medium after 18 hours of incubation at 35°C C. Yellow color in the medium after 24 hours of incubation at 35°C D. Green color in the medium after 18 hours of incubation at 35°C

A. Blue color in the medium after 24 hours of incubation at 35°C

6. In the test for urease production, ammonia reacts to form which product? A. Ammonium citrate B. Ammonium carbonate C. Ammonium oxalate D. Ammonium nitrate

B. Ammonium carbonate

7. Which of the following reagents is added to detect the production of indole? A. p-Dimethylaminobenzaldehyde B. Bromcresol purple C. Methyl red D. Cytochrome oxidase

A. p-Dimethylaminobenzaldehyde

8. Decarboxylation of the amino acids lysine, ornithine, and arginine results in the formation of: A. Ammonia B. Urea C. Carbonate D. Amines

D. Amines

9. Lysine iron agar (LIA) showing a purple slant and a blackened butt indicates: A. Escherichia coli B. Citrobacter spp. C. Salmonella spp. D. Proteus spp.

C. Salmonella spp.

10. Putrescine is an alkaline amine product of which bacterial enzyme? A. Arginine decarboxylase B. Phenylalanine deaminase C. Ornithine decarboxylase D. Lysine decarboxylase

C. Ornithine decarboxylase

11. Which genera are positive for phenylalanine deaminase? A. Enterobacter, Escherichia, and Salmonella B. Morganella, Providencia, and Proteus C. Klebsiella and Enterobacter D. Proteus, Escherichia, and Shigella

B. Morganella, Providencia, and Proteus

12. Kligler iron agar (KIA) differs from triple-sugar iron agar (TSI) in the: A. Ratio of lactose to glucose B. Ability to detect H2S production C. Use of sucrose in the medium D. Color reaction denoting production of acid

C. Use of sucrose in the medium

13. The malonate test is most useful in differentiating which members of the Enterobacteriaceae family? A. Shigella B. Proteus C. Salmonella subgroups 2, 3 (the former Arizona) D. Serratia

C. Salmonella subgroups 2, 3 (the former Arizona)

14. Which genera of the Enterobacteriaceae family are known to cause diarrhea and are considered enteric pathogens? A. Enterobacter, Klebsiella, Providencia, and Proteus B. Escherichia, Salmonella, Shigella, and Yersinia C. Pseudomonas, Moraxella, Acinetobacter, and Aeromonas D. Enterobacter, Citrobacter, and Morganella

B. Escherichia, Salmonella, Shigella, and Yersinia

15. An isolate of E. coli recovered from the stool of a patient with severe bloody diarrhea should be tested for which sugar before sending it to a reference laboratory for serotyping? A. Sorbitol (fermentation) B. Mannitol (oxidation) C. Raffinose (fermentation) D. Sucrose (fermentation)

A. Sorbitol (fermentation)

16. Care must be taken when identifying biochemical isolates of Shigella because serological cross reactions occur with: A. Escherichia coli B. Salmonella spp. C. Pseudomonas spp. D. Proteus spp.

A. Escherichia coli

17. Which species of Shigella is most commonly associated with diarrheal disease in the United States? A. Shigella dysenteriae B. Shigella flexneri C. Shigella boydii D. Shigella sonnei

D. Shigella sonnei

18. Which of the following tests best differentiates Shigella species from E. coli? A. H2S, VP, citrate, and urease B. Lactose, indole, ONPG, and motility C. Hydrogen sulfide, MR, citrate, and urease D. Gas, citrate, and VP

B. Lactose, indole, ONPG, and motility

19. Which genera of Enterobacteriaceae are usually nonmotile at 36°C? A. Shigella, Klebsiella, and Yersinia B. Escherichia, Edwardsiella, and Enterobacter C. Proteus, Providencia, and Salmonella D. Serratia, Morganella, and Hafnia

A. Shigella, Klebsiella, and Yersinia

20. Fever, abdominal cramping, watery stools, and fluid and electrolyte loss preceded by bloody stools 2 to 3 days before is characteristic of shigellosis but may also result from infection with: A. Campylobacter spp. B. Salmonella spp. C. Proteus spp. D. Yersinia spp.

A. Campylobacter spp.

21. Cold enrichment of feces (incubation at 4°C) in phosphate-buffered saline prior to subculture onto enteric media enhances the recovery of: A. Enterotoxigenic Escherichia coli B. Salmonella paratyphi C. Hafnia alvei D. Yersinia enterocolitica

D. Yersinia enterocolitica

22. Which group of tests, along with colonial morphology on primary media, aids most in the rapid identification of Enterobacteriaceae? A. MR and VP, urease, and blood agar plate B. Phenylalanine deaminase, urease, and CDC agar plate C. Bacitracin, β-lactamase, and MacConkey agar plate D. Indole, oxidase, MacConkey, and blood agar plates

D. Indole, oxidase, MacConkey, and blood agar plates

23. A routine, complete stool culture procedure should include media for the isolation of E. coli O157:H7 as well as: A. Salmonella, Shigella, Yersinia, Campylobacter, and Staphylococcus aureus B. Vibrio cholerae, Brucella, and Yersinia spp. C. Staphylococcus aureus, group B streptococci, and group D streptococci D. Clostridium difficile, Clostridium perfringens, and Yersinia spp

A. Salmonella, Shigella, Yersinia, Campylobacter, and Staphylococcus aureus

24. Which group of tests best identifies the Morganella and Proteus genera? A. Motility, urease, and phenylalanine deaminase B. Malonate, glucose fermentation, and deoxyribonuclease (DNase) C. Indole, oxidase, MR, and VP D. Indole, citrate, and urease

A. Motility, urease, and phenylalanine deaminase

25. Which group of tests best differentiates Enterobacter aerogenes from Edwardsiella tarda? A. Motility, citrate, and urease B. H2S production, sucrose fermentation, indole, and VP C. Lysine decarboxylase, urease, and arginine dihydrolase D. Motility, H2S production, and DNase

B. H2S production, sucrose fermentation, indole, and VP

26. Cronobacter sakazakii (formerly Enterobacter sakazakii) can best be differentiated from Enterobacter cloacae by which of the following characteristics? A. Yellow pigmentation and negative sorbitol fermentation B. Pink pigmentation and positive arginine dihydrolase C. Yellow pigmentation and positive urease D. H2S production on TSI

A. Yellow pigmentation and negative sorbitol fermentation

27. Members of the genus Cedecea are best differentiated from Serratia spp. by which test result? A. Positive motility B. Positive urease C. Positive phenylalanine deaminase D. Negative DNase

D. Negative DNase

28. Which of the following organisms is often confused with the Salmonella species biochemically and on plated media? A. Escherichia coli B. Citrobacter freundii C. Enterobacter cloacae D. Shigella dysenteriae

B. Citrobacter freundii

29. A gram-negative rod is recovered from a catheterized urine sample from a nursing home patient. The lactose-negative isolate tested positive for indole, urease, ornithine decarboxylase, and phenylalanine deaminase and negative for H2S. The most probable identification is: A. Edwardsiella spp. B. Morganella spp. C. Ewingella spp. D. Shigella spp.

B. Morganella spp.

30. Which single test best separates Klebsiella oxytoca from K. pneumoniae? A. Urease B. Sucrose C. Citrate D. Indole

D. Indole

31. Which of the following organisms, found in normal fecal flora, may be mistaken biochemically for the genus Yersinia? A. Klebsiella spp. B. Proteus spp. C. Escherichia coli D. Enterobacter spp.

B. Proteus spp.

32. Why might it be necessary for both pink (lactose-positive) and colorless (lactose- negative) colonies from an initial stool culture on MacConkey agar to be subcultured and tested further for possible pathogens? A. Most Shigella strains are lactose positive B. Most Salmonella strains are maltose negative C. Most Proteus spp. are lactose negative D. Pathogenic Escherichia coli can be lactose positive or lactose negative

D. Pathogenic Escherichia coli can be lactose positive or lactose negative

33. Which agar that is used for routine stool cultures is the medium of choice for the isolation of Yersinia strains from stool specimens? A. Salmonella–Shigella agar B. Hektoen enteric agar C. MacConkey agar D. CNA agar

C. MacConkey agar

34. Which organism is sometimes mistaken for Salmonella and will agglutinate in Salmonella polyvalent antiserum? A. Citrobacter freundii strains B. Proteus mirabilis strains C. Shigella sonnei strains D. Escherichia coli

A. Citrobacter freundii strains

35. A bloody stool cultured from a 26-year-old woman after 3 days of severe diarrhea showed the following results at 48 hours after being plated on the following media: ● MacConkey agar: Little normal flora with many non–lactose- fermenting colonies ● Hektoen enteric agar: Many blue-green colonies ● Campylobacter blood agar and C. difficile agar: No growth ● Clear colonies (from MacConkey agar): Negative for oxidase,indole, urease, motility, and H2S The most likely identification is: A. Shigella spp. B. Salmonella spp. C. Proteus spp. D. Escherichia coli

A. Shigella spp.

36. Which one of the following organisms (are) is generally positive for β glycosidase (utilizes lactose)? A. Salmonella spp. B. Shigella spp. C. Proteus spp. D. Escherichia coli

D. Escherichia coli

37. In the Kauffmann-White schema, the combined antigens used for serological identification of the Salmonella spp. are: A. O antigens B. H antigens C. Vi and H antigens D. O, Vi, and H antigens

D. O, Vi, and H antigens

38. The drugs of choice for treatment of infections with Enterobacteriaceae are: A. Aminoglycosides, sulfamethoxazole-trimethoprim, third-generation cephalosporins B. Ampicillin and nalidixic acid C. Streptomycin and isoniazid (isonicotinylhydrazide [INH]) D. Chloramphenicol, ampicillin, and colistin

A. Aminoglycosides, sulfamethoxazole-trimethoprim, third-generation cephalosporins

39. The Shiga-like toxin (verotoxin) is produced mainly by which Enterobacteriaceae species? A. Klebsiella pneumoniae B. Escherichia coli C. Salmonella typhimurium D. Enterobacter cloacae

B. Escherichia coli

40. Infections caused by Y. pestis are rare in the United States. Those cases that do occur are most frequently located in which region? A. New Mexico, Arizona, and California B. Alaska, Oregon, and Utah C. North and South Carolina and Virginia D. Ohio, Michigan, and Indiana

A. New Mexico, Arizona, and California

41. A leg culture from a nursing home patient grew gram-negative rods on MacConkey agar as pink to dark pink oxidase-negative colonies. Given the following results, which is the most likely organism? A. Serratia marcescens B. Proteus vulgaris C. Enterobacter cloacae D. Klebsiella pneumoniae

D. Klebsiella pneumoniae

42. Four blood cultures were taken over a 24-hour period from a 20-year-old woman with severe diarrhea. The cultures grew motile (room temperature), gram-negative rods. A urine specimen obtained via catheterization also showed gram-negative rods (100,000 col/mL). Given the following results, which is the most likely organism? A. Proteus vulgaris B. Salmonella typhi C. Yersinia enterocolitica D. Escherichia coli

D. Escherichia coli

43. A stool culture from a 30-year-old man suffering from bloody mucoid diarrhea gave the following results on differential enteric media: ● MacConkey agar = clear colonies ● XLD agar = clear colonies ● Hektoen agar = green colonies ● Salmonella–Shigella agar = . Which tests are most appropriate for identification of this enteric pathogen? A. TSI, motility, indole, urease, Shigella typing with polyvalent sera B. TSI, motility, indole, lysine, Salmonella typing with polyvalent sera C. TSI, indole, MR, VP, citrate D. TSI, indole, MR, and urease

A. TSI, motility, indole, urease, Shigella typing with polyvalent sera

44. A leg-wound culture from a hospitalized 70-year-old man with diabetes grew motile, lactose-negative colonies on MacConkey agar. Given the following biochemical reactions at 24 hours, what is the most probable organism? A. Proteus vulgaris B. Serratia marcescens C. Proteus mirabilis D. Enterobacter cloacae

B. Serratia marcescens

45. Three blood culture specimens taken from a 30-year-old patient with cancer receiving chemotherapy and admitted with a urinary tract infection (UTI) grew lactose-negative, motile, gram-negative rods prior to antibiotic therapy. Given the following biochemical reactions, which is the most likely organism? A. Proteus vulgaris B. Proteus mirabilis C. Serratia marcescens D. Klebsiella pneumoniae

A. Proteus vulgaris

46. Three consecutive stool cultures from a 25-year-old male patient produced scant normal fecal flora on MacConkey and Hektoen agars. However, colonies on CIN agar displayed “bull’s eye” colonies after 48 hours of incubation. The patient had been suffering from enterocolitis with fever, diarrhea, and abdominal pain for 2 days. What is the most likely identification of this gram-negative rod? A. Escherichia coli B. Proteus mirabilis C. Yersinia enterocolitica D. Klebsiella pneumoniae

C. Yersinia enterocolitica

47. A 6-year-old female patient was admitted to the hospital following 2 days of severe diarrhea. Cultures from three consecutive stool samples contained blood and mucus. Patient history revealed that she had eaten a hamburger at a fast-food restaurant 3 days earlier. Which pathogen is most likely responsible for the following results? Growth on: ● XLD agar = Yellow colonies ● HE agar = Yellow colonies ● Mac agar = Light pink and dark pink colonies ● Mac with sorbitol agar = Few dark pink and many colorless colonies A. Salmonella spp. B. Shigella spp. C. Escherichia coli O157:H7 D. Yersinia enterocolitica

C. Escherichia coli O157:H7

48. Following a 2-week camping trip to the southwest United States, a 65-year-old male patient was hospitalized with a high fever and an inflammatory swelling of the axilla and groin lymph nodes. Several blood cultures were obtained, and cultures showed growth of gram-negative rods resembling “closed safety pins.” The organism grew on MacConkey agar showing non–lactose-fermenting colonies. Testing demonstrated a nonmotile rod that was biochemically inert. What is the most likely pathogen identified? A. Yersinia pestis B. Klebsiella pneumoniae C. Proteus vulgaris D. Morganella morganii

A. Yersinia pestis

49. The majority of clinical laboratories with a microbiology department should have the capability of serotyping which pathogenic Enterobacteriaceae species? A. Yersinia enterocolitica, Shigella spp. B. Escherichia coli O157:H7, Salmonella spp., Shigella spp. C. Yersinia pestis, Salmonella spp. D. Edwardsiella spp., Salmonella spp.

B. Escherichia coli O157:H7, Salmonella spp., Shigella spp.

50. Direct spread of pneumonic plague disease occurs by which route? A. Fecal–oral route B. Rat bite C. Ingestion of contaminated tissue D. Inhalation of contaminated airborne droplets

D. Inhalation of contaminated airborne droplets

51. Which isolates of the Enterobacteriaceae family most commonly produce extended- spectrum β-lactamase (ESBL)? A. Escherichia coli and Klebsiella pneumoniae B. Yersinia enterocolitica and Yersinia pestis C. Morganella morganii and Proteus vulgaris D. Salmonella typhi and Shigella sonnei

A. Escherichia coli and Klebsiella pneumoniae

52. Additional methods of definitive identification for the Enterobacteriaceae family include which of the following: A. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI- TOF-MS) B. Serodiagnosis C. Nucleic acid–based studies D. All of the above

D. All of the above

53. Which of the following Shigella spp. serotypes is the most often isolated in the United States? A. Serotype A (Shigella dysenteriae) B. Serotype B (Shigella flexneri) C. Serotype C (Shigella boydii) D. Serotype D (Shigella sonnei)

D. Serotype D (Shigella sonnei)

54. Which organism is transmitted by ingesting undercooked ground beef or raw milk resulting in inflammation and bleeding of the mucosa of the large intestine (i.e., hemorrhagic colitis) which can also lead to hemolytic uremic syndrome (HUS). A. Escherichia coli (STEC)—Shiga toxin B. Escherichia coli (ETEC)—enterotoxigenic C. Escherichia coli (EAEC)—enteroaggregative D. Proteus mirabilis

A. Escherichia coli (STEC)—Shiga toxin

55. This organism is transmitted by ingesting contaminated fresh water and/or shell fish, resulting in watery, dysentery-like stools and chronic diarrhea. Culture on stool media and initial testing show the following results: ● MacConkey agar = Both lactose-fermenting and non–lactose-fermenting colonies ● Sheep blood agar = Nonhemolytic, shiny, opaque, smooth, nonspreading ● Oxidase = + DNase = Neg ● String test = Neg The most likely preliminary identification is? A. Proteus vulgaris B. Escherichia coli C. Salmonella spp. D. Plesiomonas shigelloides

D. Plesiomonas shigelloides

1. What are the most appropriate screening tests to presumptively differentiate and identify the nonfermentative gram-negative bacilli (NFB) from the Enterobacteriaceae species? A. Catalase, decarboxylation of arginine, growth on blood agar B. Motility, urease, morphology on blood agar C. Oxidase, TSI, nitrate reduction, growth on MacConkey agar D. Oxidase, indole, and growth on blood agar

C. Oxidase, TSI, nitrate reduction, growth on MacConkey agar

2. Presumptive tests used for identification of the Pseudomonas spp. are: A. Oxidase, oxidation–fermentation (OF) glucose (open), OF glucose (sealed), motility, pigment production B. Growth on blood agar plate (BAP) and eosin–methylene blue (EMB) agars, lysine decarboxylation, catalase C. Growth on MacConkey, EMB, and XLD agars and motility D. Growth on mannitol salt agar and flagellar stain

A. Oxidase, oxidation–fermentation (OF) glucose (open), OF glucose (sealed), motility, pigment production

3. Which tests are most appropriate to differentiate between Pseudomonas aeruginosa and Pseudomonas putida? A. Oxidase, motility, pyoverdin B. Oxidase, motility, lactose C. Oxidase, ONPG, DNase D. Mannitol, nitrate reduction, growth at 42°C

D. Mannitol, nitrate reduction, growth at 42°C

4. Which test group best differentiates Acinetobacter spp. from P. aeruginosa? A. Oxidase, motility, nitrate reduction B. MacConkey growth, 37°C growth, catalase C. Blood agar growth, oxidase, catalase D. Oxidase, TSI, MacConkey growth

A. Oxidase, motility, nitrate reduction

5. In addition to motility, which test best differentiates Acinetobacter spp. and Alcaligenes faecalis? A. Triple sugar iron agar B. Oxidase C. Urease D. Flagellar stain

B. Oxidase

6. The most noted differences between P. aeruginosa and Stenotrophomonas maltophilia are: A. Oxidase, catalase, and TSI B. Oxidase, catalase, and ONPG C. Oxidase, 42°C growth, and polar tuft of flagella D. Catalase, TSI, and pigment

C. Oxidase, 42°C growth, and polar tuft of flagella

7. Which nonfermentative bacillus is usually associated with a lung infection related to cystic fibrosis (CF)? A. Pseudomonas fluorescens B. Pseudomonas aeruginosa C. Pseudomonas putida D. Burkholderia pseudomallei

B. Pseudomonas aeruginosa

8. A nonfermenter recovered from an eye wound is oxidase positive, motile with polar monotrichous flagella, and grows at 42°C. Colonies are dry, wrinkled or smooth, buff to light brown, and are difficult to remove from the agar. In which DNA homology group should this organism be placed? A. Pseudomonas stutzeri B. Pseudomonas fluorescens C. Pseudomonas putida D. Burkholderia pseudomallei

A. Pseudomonas stutzeri

9. Which organism is associated with immunodeficiency syndromes and melioidosis (a glanders-like disease prevalent in Southeast Asia and northern Australia)? A. Pseudomonas aeruginosa B. Pseudomonas stutzeri C. Pseudomonas putida D. Burkholderia pseudomallei

D. Burkholderia pseudomallei

10. Which characteristics/biochemical tests are used to differentiate Burkholderia cepacia from S. maltophilia? A. Pigment on blood agar, oxidase, DNase B. Pigment on MacConkey agar, flagellar stain, motility C. Glucose, maltose, lysine decarboxylase D. Triple-sugar iron agar, motility, oxidase

A. Pigment on blood agar, oxidase, DNase

The following results were obtained from a pure culture of gram-negative rods recovered from the pulmonary secretions of a 10-year-old cystic fibrosis patient with pneumonia: Which is the most likely organism? A. Burkholderia pseudomallei B. Pseudomonas stutzeri C. Burkholderia cepacia D. Pseudomonas aeruginosa

D. Pseudomonas aeruginosa

12. Alcaligenes faecalis (formerly A. odorans) is distinguished from Bordetella bronchiseptica with which test? A. Urease (rapid) B. Oxidase C. Growth on MacConkey agar D. Motility

A. Urease (rapid)

13. Chryseobacterium spp. are easily distinguished from Acinetobacter spp. by which of the following two tests? A. Oxidase, growth on MacConkey agar B. Oxidase and OF (glucose) C. TSI and urea hydrolysis D. TSI and VP

A. Oxidase, growth on MacConkey agar

14. A gram-negative coccobacillus was recovered on chocolate agar from the CSF of an immunosuppressed patient. The organism was nonmotile and positive for indophenol oxidase but failed to grow on MacConkey agar. The organism was highly susceptible to penicillin. The most probable identification is: A. Acinetobacter spp. B. Pseudomonas aeruginosa C. Pseudomonas stutzeri D. Moraxella lacunata

D. Moraxella lacunata

15. Cetrimide agar is used as a selective isolation agar for which organism? A. Acinetobacter spp. B. Pseudomonas aeruginosa C. Moraxella spp. D. Stenotrophomonas maltophilia

B. Pseudomonas aeruginosa

A specimen from a 15-year-old female burn patient was cultured after débridement, and the following results were Obtained: These results indicate which of the following organisms?. A. Acinetobacter spp. B. Moraxella lacunata C. Pseudomonas aeruginosa D. Alcaligenes spp.

C. Pseudomonas aeruginosa

17. A yellow pigment–producing organism, growing on chocolate agar, testing oxidase positive, nonmotile and does not grow on MacConkey agar was recovered from the blood of a neonate. What is the most likely organism? A. Acinetobacter spp. B. Pseudomonas aeruginosa C. Burkholderia cepacia D. Elizabethkingia (formerly Chryseobacterium) meningosepticum

D. Elizabethkingia (formerly Chryseobacterium) meningosepticum

18. Which reagent(s) is (are) used to develop the red color indicative of a positive reaction in the nitrate reduction test? A. Sulfanilic acid and α-naphthylamine B. Ehrlich and Kovac reagents C. o-Nitrophenyl-β-D-galactopyranoside D. Kovac reagent

A. Sulfanilic acid and α-naphthylamine

A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar that gave the following results: The most likely identification is: A. Shewanella putrefaciens B. Acinetobacter spp. C. Pseudomonas aeruginosa D. Chryseobacterium spp.

A. Shewanella putrefaciens

20. Chryseobacterium spp. and B. cepacia are easily differentiated by which test? A. Motility B. OF glucose C. Oxidase D. Cetrimide agar

A. Motility

21. A 15-year-old female complained of a severe eye irritation after removing her soft contact lenses. A swab specimen of the infected right eye was obtained by an ophthalmologist, who ordered culture and sensitivity testing. The culture was plated on blood agar and MacConkey agar. At 24 hours, growth of a gram-negative rod that tested positive for cytochrome oxidase was noted. The Mueller-Hinton sensitivity plate showed a bluish-green “lawn” of growth that proved highly resistant to most of the antibiotics tested except amikacin, tobramycin, and ciprofloxacin. What is the most likely identification? A. Burkholderia cepacia B. Pseudomonas aeruginosa C. Stenotrophomonas maltophilia D. Acinetobacter spp.

Pseudomonas aeruginosa

22. Which of the listed Pseudomonas spp. is associated with the following virulence factors: exotoxin A, endotoxins, proteolytic enzymes, antimicrobial resistance, and production of alginate? A. Pseudomonas fluorescens B. Pseudomonas putida C. Pseudomonas stutzeri D. Pseudomonas aeruginosa

D. Pseudomonas aeruginosa

23. A 20-year-old horse groomer exhibited a “glanders-like” infection. His history indicated he had suffered several open wounds on his hands 2 weeks before the swelling of his lymph nodes. A gram-negative rod was recovered from a blood culture that grew well on blood and MacConkey agars. Most of the biochemical tests were negative, including the cytochrome oxidase test. What is the most likely identification? A. Burkholderia mallei B. Pseudomonas aeruginosa C. Pseudomonas stutzeri D. Burkholderia pseudomallei

A. Burkholderia mallei

24. A Vietnam War veteran presented with a “glanders-like” infection (melioidosis). Several blood cultures produced gram-negative rods that were positive for cytochrome oxidase, oxidized glucose and xylose, and grew at 42°C. What is the most likely organism? A. Stenotrophomonas maltophilia B. Burkholderia pseudomallei C. Pseudomonas aeruginosa D. Acinetobacter spp.

B. Burkholderia pseudomallei

25. Cytochrome oxidase-positive, nonfermentative gram-negative bacilli were recovered from the stool of a patient with CF. The isolates produced wet (mucoidy) light blue colonies on tryptic soy agar. Which identification is most likely? A. Acinetobacter spp. B. Pseudomonas putida C. Pseudomonas stutzeri D. Pseudomonas aeruginosa

D. Pseudomonas aeruginosa

26. Several postoperative hospitalized patients were colonized with gram-negative coccobacilli growing on MacConkey agar. Specimens were obtained from blood, urine, and wound sites. Testing revealed oxidase negative, nonmotile organisms. Which of the following is the most likely cause of the nosocomial infections? A. Acinetobacter spp. B. Pseudomonas aeruginosa C. Burkholderia cepacia D. Pseudomonas putida

A. Acinetobacter spp.

27. A nosocomial infection involving an 80-year-old female patient, recovering from pneumonia, produced many oxidase-negative colonies on MacConkey agar. Further testing results are: ● Motility = + ● Maltose = + ● Resistant to most beta-lactams ● Glucose = + ● Resistant to most aminoglycosides The most likely identification is: A. Acinetobacter spp. B. Stenotrophomonas maltophilia C. Pseudomonas aeruginosa D. Burkholderia gladioli

B. Stenotrophomonas maltophilia