microbio harr

The aseptic collection of blood cultures requires that the skin be cleansed with:
A. 2% iodin 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

Correct Answer: B

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 sec
B. 30 sec
C. 60 sec
D. 5 min

Correct Answer: C

What is the purpose of adding 0.025%-0.050% sodium polyanetholsulfanate (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

Correct Answer: A

A flexible calcium alginate nasopharyngeal swab in 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

Correct Answer: C

Semisolid transport media such as Amies, Stuart, or Cary-Blair are suitable for the transport of swabs for culture of most pathogen except:
A. Neisseria gonorrhoeae
B. Enterobacteriaceae
C. Camplyobacter fetus
D. Streptococcus pneumoniae

Correct Answer: A

Select the method of choice for recovery of anaerobic bacteria from a deep abscess.
A. Cotton fiver swab or the abscess area
B. Skin snip of the surface tissue
C. Needle aspirate after surface decontamination
D. Swab of the scalpel used for debridement

Correct Answer: C

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, Campy, colistin-nalidixic acid (CNA) agars
C. CNA and Christensen urea agars and thioglycollate media
D. Blood, Campy, Mueller-Hinton agars, and thioglycollate media

Correct Answer: B

Select the media of choice for recovery of Vibrio cholerae form 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 selenite-F (SEL) broth
D. CNA agar

Correct Answer: B

Colistin-nalidixic acid agar (CNA) is used primarily for the recovery of:
A. Neisseria species
B. Enterobacteriaceae
C. Pseudomonas aeruginosa
D. Staphylococcus

Correct Answer: D

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

Correct Answer: A

All of the following are appropriate when attempting to isolate N. gonorrheae from a genital specimen except:
A. Transport the genital swab in charcoal transport medium
B. Plate the specimen on modified Thayer-Marin (MTM) medium
C. Plate the specimen on New York City or Martin-Lewis agar
D. Culture specimens in ambient oxygen at 37C

Correct Answer: D

Chocolate agar and modified Thayer-Martin 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

Correct Answer: B

Cycloserine-cefoxitin-fructose agar (CCFA) is used for the recovery of:
A. Yersinia enterocolitica
B. Yersinia intermedia
C. Clostridium perfringens
D. Clostridium difficile

Correct Answer: D

Deoxycholate agar (DCA) is useful for the isolation of:
A. Enterobacteriaceae
B. Enterococcus spp.
C. Staphylococcus spp.
D. Neisseria spp.

Correct Answer: A

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

Correct Answer: C

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

Correct Answer: B

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.

Correct Answer: B

Which procedure is appropriate for culture of genital specimens in order to recover Chlamydia spp.?
A. Inoculate cycloheximide-treated McCoy cells
B. Plate onto blood and chocolate agar
C. Inoculate into thioglycollate (THIO) broth
D. Plate onto modified Thayer-Martin agar within 24 hours

Correct Answer: A

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 nutrient

Correct Answer: D

Cerebrospinal fluid (CSF) should be cultured immediately, but if delayed the specimen should be:
A. Refrigerated at 4C to 6C
B. Frozen at -20C
C. Stored at room temperature for no longer than 24 hours
D. Incubated at 37C and cultured as soon as possible

Correct Answer: D

The most sensitive method for the detection of B-lactamase in bacteria is by the use of:
A. Chromogenic cephalosporin
B. Penicillin
C. Oxidase
D. Chloramphenicol acetyltransferase

Correct Answer: A

The breakpoint of an antimicrobial drug refers to:
A. The amount needed to cause bacteriostasis
B. A minimum inhibitory concentration (MIC) of 16 ug/mL or greater
C. A MIC of 64 ug/mL or greater
D. The level of drug that is achievable in serum

Correct Answer: D

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

Correct Answer: D

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 are 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

Correct Answer: A

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

Correct Answer: D

Select the medium best suited for the recovery of Yersinia entercolitica from a patient with gastroenteritis.
A. Hektoen agar
B. Cefsulodin-Irgasan-Novoviocin (CIN) agar
C. Blood agar
D. Eosinmethylene blue agar

Correct Answer: B

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

Correct Answer: D

SITUATION: Abdominal pain, fever, vomiting, and nausea prompted an elderly male to seek medical attention. A water stool specimen producing no fecal leukocytes or erythrocytes was cultured and grew a predominance of gram-negative fermentative bacilli. The colonies were beta-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.

Correct Answer:A

SITUATION: Several attendees of a medical conference in the Gulf coast area became ill after frequenting a seafood restaurant. A presumptive identification of Vibrio cholera was made after stool specimens form 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

Correct Answer: A

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. XLD agar
B. MacConkey agar
C. MacConkey agar with sorbitol
D. Hektoen agar

Correct Answer: C

Biochemically, the Enterobacteriaceae 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

Correct Answer: A

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

Correct Answer: B

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

Correct Answer: A

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

Correct Answer: D

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

Correct Answer: A

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

Correct Answer: B

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

Correct Answer: A

Decarboxylation of the amino acids lysine, ornithine, and arginine results in the formation of:
A. Ammonia
B. Urea
C. CO2
D. Amines

Correct Answer: D

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

Correct Answer: C

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

Correct Answer: C

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

Correct Answer: B

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

Correct Answer: C

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

Correct Answer: C

Which genera of the Enterobacteriaceae 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, Morganella

Correct Answer: B

An isolate of E. coli recovered form 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)

Correct Answer: A

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

Correct Answer: A

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

Correct Answer: D

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

Correct Answer: B

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

Correct Answer: A

Fever, abdominal cramping, watery stools, and fluid and electrolyte loss preceded by bloody stools 2-3 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.

Correct Answer: A

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

Correct Answer: D

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

Correct Answer: D

A routine, complete stool culture procedure should include media for the isolation of E. coli 0157:H7 as well as:
A. Salmonella, Shigella, Yersinia, Campylobacter, and Staphylococcus aureus
B. Vibrio cholerae, Brucella, and Yersinia spp.
C. S. aureus, group B streptococci, and group D streptococci
D. Clostridium difficile, Clostridium perfringens, and Yersinia spp.

Correct Answer: A

Which group of test 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

Correct Answer: A

Which group of test best differentiates Enterobacter aerogenes form Edwardsiella tarda?
A. Motility, citrate, and urease
B. Hydrogen sulfide (H2S) production, sucrose fermentation, indole, and VP
C. Lysine decarboxylase, urease, arginine
D. Motility, H2S production, and DNase

Correct Answer: B

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

Correct Answer: A

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

Correct Answer: D

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

Correct Answer: B

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 phenylalanime deaminase and negative for H2S. The most probable identification is:
A. Edwardsiella spp.
B. Morganella spp.
C. Ewingella spp.
D. Shigella spp.

Correct Answer: B

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

Correct Answer: D

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. E. coli
D. Enterobacter spp

Correct Answer: B

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 E. coli can be lactose positive or lactose negative

Correct Answer: D

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

Correct Answer: C

Which organism is sometimes mistaken for Salmonella and will agglutinate in Salmonella polyvalent antiserum?
A. C. feundii strains
B. Proteus mirabilis strains
C. S. sonnei strains
D. E. coli

Correct Answer: A

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) tested negative for oxidase, indole, urease, motility, and H2S
A. Shigella spp.
B. Salmonella spp.
C. Proteus spp.
D. E. coli

Correct Answer: A

Which of the following organism are generally positive for B-galactosidase?
A. Salmonella spp.
B. Shigella spp.
C. Proteus spp.
D. E. coli

Correct Answer: D

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

Correct Answer: D

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

Correct Answer: A

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

Correct Answer: B

Infections caused by Yersinia 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

Correct Answer: A

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?
-TIS\=A/A
-VP\=+
-Urease\=+
-Indole\=Neg
-Citrate\=+
-Motility\=Neg
-MR\=Neg
-H2S\=Neg
Antibiotic susceptibility: resistant to carbenicillin and ampicillin
A. Serratia marcescens
B. Proteus vulgaris
C. Enterobacter cloacae
D. Klebsiella pneumoniae

Correct Answer: D

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 by catheterization also showed gram-negative rods, 100,000 col/mL. Given the following results, which is the most likely organism?
-TSI\=A/A gas
-VP\=Neg
-H2S\=Neg
-Urease\=Neg
-Phenylalnine deaminase\=Neg
-Indole\=+
-MR\=+
-Citrate\=Neg
-Lysine decarboxylase\=+
A. Proteus vulgaris
B. Salmonella typhi
C. Yersinia enterocolitica
D. E. coli

Correct Answer: D

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\=small, clear colonies
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

Correct Answer: A

A leg-wound culture from a hospitalized 70-year-old diabetic man grew motile, lactose-negative colonies on MacConkey agar. Given the following biochemical reactions at 24 hours, what is the most probable organism?
-H2S (TSI)\=Neg
-MR\=Neg
-DNase\=+
-Urease\=Neg
-Phenylalanine deaminase\=Neg
-Ornithine and lysin decarboxylase\=+
-Arginine decarboxylase\=Neg
-Gelatin hydrolysis\=+
-Indole\=Neg
-VP\=+
-Citrate\=+
A. Proteus vulgaris
B. Serratia marcescens
C. Proteus mirabilis
D. Enterobacter cloacae

Correct Answer: B

Three blood cultures taken from a 30-year-old cancer patient receiving chemotherapy and admitted with a urinary tract infection grew lactose-negative, motile, gram-negative rods prior to antibiotic therapy. Given the following biochemical reactions, which is the most likely organism?
-H2S (TSI)\=+
-VP\=Neg
-DNase\=+
-Gelatin hydrolysis\=+
-Ornithine decarboxylase\=Neg
-Indole\=+
-Citrate\=Neg
-Phenylalanine deaminase\=+
-MR\=+
-Urease\=+
A. Proteus vulgaris
B. Proteus mirabilis
C. Serratia marcescens
D. Klebsiella pneumoniae

Correct Answer: A

Three consecutive stool cultures form a 25-year-old male patient produced scant normal fecal flora on MacConkey and Hektoen agars. However, colonies on CIN agar (cefsulodin-irgasan-novobiocin) displayed "bulls-eye" colonies after 48 hours 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. E. coli
B. Proteus mirabilis
C. Yersinia enterocolitica
D. Klebsiella pneumoniae

Correct Answer: C

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 a hamburger lunch 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. E. coli 0157:H7
D. Yersinia enterocolitica

Correct Answer: C

Following a 2-week camping trip to the Southwest (US), 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, resulting in growth of gram-negative rods resembling "closed safety pins." The organism grew on MacConkey's agar showing non-lactose-fermenting colonies. Testing demonstrated a nonmotile rod that was biochemically inert. What is the most likely identification?
A. Yersinia pestis
B. Klebsiella pneumoniae
C. Proteus vulgaris
D. Morganella morganii

Correct Answer: A

The majority of clinical laboratories with a microbiology department should have the capability o serotyping which pathogenic Enterobacteriaceae?
A. Yersinia enterocolitica, Shigella spp.
B. E. coli 0157:H7, Salmonella spp., Shigella spp.
C. Yersinia pestis, Salmonella spp.
D. Edwardsiella spp., Salmonella spp.

Correct Answer: B

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

Correct Answer: D

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

Correct Answer: A

What are the most appropriate screening test to presumptively differentiate and identify the nonfermentative gram-negative bacilli (NFB) from the Enterbacteriaceae?
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

Correct Answer: C

Presumptive test used for identification of 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 (EMB) agars, lysine decarboxylation, catalase
C. Growth on macConkey, EMB, and XLD agars, and motility
D. Growth on mannitol slat agar and flagellar stain

Correct Answer: A

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

Correct Answer: D

Which test group best differentiates Acinetobacter baumanii from P. aeruginosa?
A. Oxidase, motility, NO3 reduction
B. MacConkey growth, 37C growth, catalase
C. Blood agar growth, oxidase, catalase
D. Oxidase, TSI, MacConkey growth

Correct Answer: A

In addition to motility, which test best differentiates Acinetobacter spp. and Alcaligenes spp.?
A. TSI
B. Oxidase
C. Catalase
D. Flagellar stain

Correct Answer: B

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

Correct Answer: C

Which Pseudomonas is usually associated with a lung infection related to cystic fibrosis?
A. P. fluorescens
B. P. aeruginosa
C. P. putida
D. Burkholderia pseudomallei

Correct Answer: B

A nonfermenter recovered form an eye wound is oxidase positive, motile with polas monotrichous flagell, and grows at 42C. Colonies are dry, wrinkled or smooth, buff to light brown in color, 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 alcaligenes
D. Pseudomonas diminuta

Correct Answer: A

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

Correct Answer: D

Which biochemical test are needed 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. TSI, motility, oxidase

Correct Answer: A

The following results were obtained form a pure culture of gram-negative rods recovered form the pulmonary secretions of a 10-year-old cystic fibrosis patient with pneumonia:
-Oxidase\=+
-Glucose OF (open)\=+
-Pigment\=Red (nonfluorescent)
-Growth at 42C\=+
-Motility \=+
-Gelatin hydrolysis\=+
-Arginie dihydrolase\=+
Flagella\=+ (polar, monotrichous)
Which is the most likely organism?
A. Burkholderia pseudomallei
B. Pseudomonas stutzeri
C. Burkholderia cepacia
D. Pseudomonas aeruginosa

Correct Answer: D

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

Correct Answer: A

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

Correct Answer: A

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

Correct Answer: D

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

Correct Answer: B

A specimen from a 15-year old female burn patine was cultured after debridement, and the following results were obtained:
-Oxidase\=+
-Catalase\=+
-Ornithine decarboxylase\=Neg
-Arginine dihydrolase\=+
-Penicillin\=Resistant
-Colistin (Polymixin B)\= Susceptible
-Lysine decarboxylase\=Neg
-Motility\=+
-Glucose\=+ for oxidation (open tube)
-Maltose\=Neg for oxidation (open tube)
-Aminoglycosides\=Susceptible
These results indicate which of the following organism?
A. Acinetobacter baumannii
B. Moraxella lacunata
C. Pseudomonas aeruginosa
D. Acinetobacter lwoffi

Correct Answer: C

A yellow pigment-producing organism that is oxidase positive, nonmotile, and does not grow on MacConkey agar is:
A. Acinetobacter baumannii
B. Acinetobacter lwoffi
C. Burkholderia cepacia
D. Chryseobacterium meningosepticum

Correct Answer: D

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 a-naphthylamine
B. Ehrilich's and Kovac's reagents
C. o-Nitrophenyl-B-D-galactopyranoside
D. Kovac's reagent

Correct Answer: A

A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar that gave the following results;
-Oxidase\=+
-KIA\=Alk/Alk (H2S)
-DNase\=+
-Growth at 42C\=Neg
-Nitrate reduction\=+
-Motility\=+ (single polar flagellum)
-Ornithine decarboxylase\=+
The most likely identification is:
A. Shewanella putrefaciens
B. Acinetobacter spp.
C. Pseudomonas aeruginosa
D. Chryseobacterium spp.

Correct Answer: A