Micro- Enterobacteriaceae Flashcards
1
Q
- 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
A
A. Ferment glucose, reduce nitrate to nitrite, and
are oxidase negative
2
Q
- 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.
A
B. Shigella spp. from some strains of Escherichia coli
3
Q
- The Voges–Proskauer (VP) test detects which
end product of glucose fermentation?
A. Acetoin
B. Nitrite
C. Acetic acid
D. Hydrogen sulfide
A
A. Acetoin
4
Q
- At which pH does the methyl red (MR) test
become positive?
A. 7.0
B. 6.5
C. 6.0
D. 4.5
A
D. 4.5
5
Q
- 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
A. Blue color in the medium after 24 hours of
incubation at 35°C
6
Q
- In the test for urease production, ammonia reacts
to form which product?
A. Ammonium citrate
B. Ammonium carbonate
C. Ammonium oxalate
D. Ammonium nitrate
A
B. Ammonium carbonate
7
Q
- 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
A. p-Dimethylaminobenzaldehyde
8
Q
- Decarboxylation of the amino acids lysine,
ornithine, and arginine results in the
formation of:
A. Ammonia
B. Urea
C. CO2
D. Amines
A
D. Amines
9
Q
- 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.
A
C. Salmonella spp.
10
Q
- Putrescine is an alkaline amine product of which
bacterial enzyme?
A. Arginine decarboxylase
B. Phenylalanine deaminase
C. Ornithine decarboxylase
D. Lysine decarboxylase
A
C. Ornithine decarboxylase
11
Q
- 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
A
B. Morganella, Providencia, and Proteus
12
Q
- 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
A
C. Use of sucrose in the medium
13
Q
- 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
A
C. Salmonella subgroups 2, 3 (the former Arizona)
14
Q
- 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, and Morganella
A
B. Escherichia, Salmonella, Shigella, and Yersinia
15
Q
- 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
A. Sorbitol (fermentation)
16
Q
- 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.
A
A. E. coli
17
Q
- 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
A
D. S. sonnei
18
Q
- Which of the following tests best differentiates
Shigella species from 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
A
B. Lactose, indole, ONPG, and motility
19
Q
- 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
A. Shigella, Klebsiella, and Yersinia
20
Q
- 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.
A
A. Campylobacter spp.
21
Q
- Cold enrichment of feces (incubation at 4°C) 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
A
D. Y. enterocolitica
22
Q
- 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, β-lactamase, and MacConkey agar
plate
D. Indole, oxidase, MacConkey, and blood agar
plates
A
D. Indole, oxidase, MacConkey, and blood agar
plates
23
Q
- 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. S. aureus, group B streptococci, and group D
streptococci
D. Clostridium difficile, Clostridium perfringens, and
Yersinia spp.
A
A. Salmonella, Shigella, Yersinia, Campylobacter,
and Staphylococcus aureus
24
Q
- 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
A. Motility, urease, and phenylalanine deaminase
25
Q
- Which group of tests best differentiates Enterobacter
aerogenes from Edwardsiella tarda?
A. Motility, citrate, and urease
B. Hydrogen sulfide (H2S) production, sucrose
fermentation, indole, and VP
C. Lysine decarboxylase, urease, and arginine
dihydrolase
D. Motility, H2S production, and DNase
A
B. Hydrogen sulfide (H2S) production, sucrose
fermentation, indole, and VP
26
Q
- 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
A. Yellow pigmentation and negative sorbitol
fermentation
27
Q
- 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
A
D. Negative DNase
28
Q
- Which of the following organisms is often
confused with the Salmonella species
biochemically and on plated media?
A. E. coli
B. Citrobacter freundii
C. Enterobacter cloacae
D. Shigella dysenteriae
A
B. Citrobacter freundii
29
Q
- 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.
A
B. Morganella spp.
30
Q
- Which single test best separates Klebsiella oxytoca
from K. pneumoniae?
A. Urease
B. Sucrose
C. Citrate
D. Indole
A
D. Indole
31
Q
- 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.
A
B. Proteus spp.
32
Q
- 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
A
D. Pathogenic E. coli can be lactose positive or
lactose negative
33
Q
- 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
A
C. MacConkey agar
34
Q
- Which organism is sometimes mistaken for
Salmonella and will agglutinate in Salmonella
polyvalent antiserum?
A. C. freundii strains
B. Proteus mirabilis strains
C. S. sonnei strains
D. E. coli
A
A. C. freundii strains
35
Q
- 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
The most likely identification is:
A. Shigella spp.
B. Salmonella spp.
C. Proteus spp.
D. E. coli
A
A. Shigella spp.
36
Q
- Which of the following organisms are generally
positive for β-galactosidase?
A. Salmonella spp.
B. Shigella spp.
C. Proteus spp.
D. E. coli
A
D. E. coli
37
Q
- 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
A
D. O, Vi, and H antigens
38
Q
- 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
A
A. Aminoglycosides, trimethoprim–sulfamethoxazole,
third-generation cephalosporins
39
Q
- The Shiga-like toxin (verotoxin) is produced
mainly by which Enterobacteriaceae?
A. Klebsiella pneumoniae
B. E. coli
C. Salmonella typhimurium
D. Enterobacter cloacae
A
B. E. coli
40
Q
- 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
A
A. New Mexico, Arizona, and California
41
Q
- 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?
TSI = A/A
Indole = Neg
MR = Neg
VP = +
Citrate = +
H2S = Neg
Urease = +
Motility = Neg
Antibiotic susceptibility: resistant to carbenicillin
and ampicillin
A. Serratia marcescens
B. Proteus vulgaris
C. Enterobacter cloacae
D. Klebsiella pneumoniae
A
D. Klebsiella pneumoniae
42
Q
- 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
Indole = +
VP = Neg
MR = +
H2S = Neg
Citrate = Neg
Urease = Neg
Lysine decarboxylase = +
Phenylalanine deaminase = Neg
A. Proteus vulgaris
B. Salmonella typhi
C. Yersinia enterocolitica
D. E. coli
A
D. E. coli
43
Q
- 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
A
A. TSI, motility, indole, urease, Shigella typing with
polyvalent sera
44
Q
- 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
Indole = Neg
MR = Neg
VP = +
DNase = +
Citrate = +
Urease = Neg
Phenylalanine deaminase = Neg
Ornithine and lysine decarboxylase = +
Arginine decarboxylase = Neg
Gelatin hydrolysis = +
A. Proteus vulgaris
B. Serratia marcescens
C. Proteus mirabilis
D. Enterobacter cloacae
A
B. Serratia marcescens
45
Q
- 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) = +
Indole = +
MR = +
VP = Neg
Citrate = Neg
Urease = +
DNase = + Phenylalanine deaminase = +
Gelatin hydrolysis = +
Ornithine decarboxylase = Neg
A. Proteus vulgaris
B. Proteus mirabilis
C. Serratia marcescens
D. Klebsiella pneumoniae
A
A. Proteus vulgaris
46
Q
- 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 (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
A
C. Yersinia enterocolitica
47
Q
- 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 O157:H7
D. Yersinia enterocolitica
A
C. E. coli O157:H7
48
Q
- 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
A
A. Yersinia pestis
49
Q
- The majority of clinical laboratories with a
microbiology department should have the
capability of serotyping which pathogenic
Enterobacteriaceae?
A. Yersinia enterocolitica, Shigella spp.
B. E. coli O157:H7, Salmonella spp., Shigella spp.
C. Yersinia pestis, Salmonella spp.
D. Edwardsiella spp., Salmonella spp
A
B. E. coli O157:H7, Salmonella spp., Shigella spp.
50
Q
- 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
A
D. Inhalation of contaminated airborne droplets
51
Q
- Which isolates of the Enterobacteriaceae family
most commonly produce extended-spectrum
β-lactamase (ESBL)?
A. E. coli and Klebsiella pneumoniae
B. Yersinia enterocolitica and Yersinia pestis
C. Morganella morganii and Proteus vulgaris
D. Salmonella typhi and Shigella sonnei
A
A. E. coli and Klebsiella pneumoniae
