Micro-Miscellaneous and Fastidious Gram-Negative Rods Flashcards
1
Q
- A visitor to South America who returned
with diarrhea is suspected of being infected with
V. cholerae. Select the best medium for recovery
and identification of this organism.
A. MacConkey agar
B. Blood agar
C. TCBS agar
D. XLD agar
A
C. TCBS agar
2
Q
- A curved gram-negative rod producing
oxidase-positive colonies on blood agar was
recovered from a stool culture. Given the
following results, what is the most likely
identification?
Lysine decarboxylase = + Arginine decarboxylase = Neg
Indole = +
KIA = Alk/Acid
VP = Neg
Lactose = Neg
Urease = ±
String test = Neg
TCBS agar = Green colonies
A. Vibrio cholerae
B. Vibrio parahaemolyticus
C. Shigella spp.
D. Salmonella spp
A
B. Vibrio parahaemolyticus
3
Q
- A gram-negative S-shaped rod recovered from
selective media for Campylobacter species gave
the following results:
Catalase = +
Oxidase = +
Motility = +
Hippurate hydrolysis = +
Growth at 42°C = + Nalidixic acid = Susceptible
Pigment = Neg
Grape odor = Neg Cephalothin = Resistant
The most likely identification is:
A. Pseudomonas aeruginosa
B. Campylobacter jejuni
C. Campylobacter fetus
D. Pseudomonas putida
A
B. Campylobacter jejuni
4
Q
4.. Which atmospheric condition is needed to recover
Campylobacter spp. from specimens inoculated
onto a Campy-selective agar at 35°C–37°C
and 42°C?
A. 5% O2, 10% CO2, and 85% N2
B. 20% O2, 10% CO2, and 70% N2
C. 20% O2, 20% CO2, and 60% N2
D. 20% O2, 5% CO2, and 75% N2
A
A. 5% O2, 10% CO2, and 85% N2
5
Q
- Which group of tests best differentiates
Helicobacter pylori from C. jejuni?
A. Catalase, oxidase, and Gram stain
B. Catalase, oxidase, and nalidixic acid sensitivity
C. Catalase, oxidase, and cephalothin sensitivity
D. Urease, nitrate, and hippurate hydrolysis
A
D. Urease, nitrate, and hippurate hydrolysis
6
Q
- Which of the following tests should be done first
in order to differentiate Aeromonas spp. from the
Enterobacteriaceae?
A. Urease
B. OF glucose
C. Oxidase
D. Catalase
A
C. Oxidase
7
Q
- Which is the best rapid test to differentiate
Plesiomonas shigelloides from a Shigella species on
selective enteric agar?
A. Oxidase
B. Indole
C. TSI
D. Urease
A
A. Oxidase
8
Q
- Which are the best two tests to differentiate
A. hydrophilia from P. shigelloides?
A. Oxidase and motility
B. DNase and VP
C. Indole and lysine decarboxylase
D. Growth on MacConkey and blood agar
A
B. DNase and VP
9
Q
- Which genus (in which most species are oxidase
and catalase positive) of small gram-negative
coccobacilli is associated mainly with animals but
may cause endocarditis, bacteremia, as well as
wound and dental infections in humans?
A. Actinobacillus
B. Pseudomonas
C. Campylobacter
D. Vibrio
A
A. Actinobacillus
10
Q
- Which of the following tests may be used to
differentiate Cardiobacterium hominis from
Actinobacillus spp.?
A. Gram stain
B. Indole
C. Anaerobic incubation
D. Oxidase
A
B. Indole
11
Q
- A mixture of slender gram-negative rods and
coccobacilli with rounded ends was recovered from
blood cultures following a patient’s root canal
surgery. Given the following results after 48 hours,
what is the most likely organism?
Catalase = Neg
Ornithine decarboxylase = +
Urease = Neg Lysine decarboxylase = +
Oxidase = + X and V requirement = Neg
Indole = Neg
Carbohydrates = Neg
(no acid produced)
Growth on blood and chocolate agar = + (with pitting
of agar)
Growth on MacConkey agar = Neg
A. Eikenella corrodens
B. Actinobacillus spp.
C. Cardiobacterium hominis
D. Proteus spp
A
A. Eikenella corrodens
12
Q
- Kingella kingae can best be differentiated from
Eikenella corrodens using which medium?
A. Sheep blood agar
B. Chocolate agar
C. MacConkey agar
D. XLD agar
A
A. Sheep blood agar
13
Q
- Kingella kingae is usually associated with which
type of infection?
A. Middle ear
B. Endocarditis
C. Meningitis
D. Urogenital
A
B. Endocarditis
14
Q
- Cultures obtained from a dog bite wound
produced yellow, tan, and slightly pink colonies
on blood and chocolate agar with a margin of
fingerlike projections appearing as a film around
the colonies. Given the following results at
24 hours, which is the most likely organism?
Oxidase = +
Catalase = +
Growth on MacConkey agar = Neg
Motility = Neg
A. Actinobacillus spp.
B. Eikenella spp.
C. Capnocytophaga spp.
D. Pseudomonas spp.
A
C. Capnocytophaga spp.
15
Q
- Smooth gray colonies showing no hemolysis are
recovered from an infected cat scratch on blood
and chocolate agar but fail to grow on MacConkey
agar. The organisms are gram-negative pleomorphic
rods that are both catalase and oxidase positive
and strongly indole positive. The most likely
organism is:
A. Capnocytophaga spp.
B. Pasteurella spp.
C. Proteus spp.
D. Pseudomonas spp.
A
B. Pasteurella spp.
16
Q
- Which media should be used to recover Bordetella
pertussis from a nasopharyngeal specimen?
A. Chocolate agar
B. Blood agar
C. MacConkey agar
D. Bordet–Gengou agar
A
D. Bordet–Gengou agar
17
Q
- Which medium is recommended for the recovery
of Brucella spp. from blood and bone marrow
specimens?
A. Biphasic Castenada bottles with Brucella broth
B. Blood culture bottles with Brucella broth
C. Bordet–Gengou agar plates and THIO broth
D. Blood culture bottles with THIO broth
A
A. Biphasic Castenada bottles with Brucella broth
18
Q
- In addition to CO2 requirements and biochemical
characteristics, Brucella melitensis and Brucella
abortus are differentiated by growth on media
containing which two dyes?
A. Basic fuchsin and thionin
B. Methylene blue and crystal violet
C. Carbol fuchsin and iodine
D. Safranin and methylene blue
A
A. Basic fuchsin and thionin
19
Q
- Which of the following amino acids are required
for growth of Francisella tularensis?
A. Leucine and ornithine
B. Arginine and lysine
C. Cysteine and cystine
D. Histidine and tryptophan
A
C. Cysteine and cystine
20
Q
- Which medium is best for recovery of Legionella
pneumophila from clinical specimens?
A. Chocolate agar
B. Bordet–Gengou agar
C. New yeast extract agar
D. Buffered charcoal–yeast extract (CYE) agar
A
D. Buffered charcoal–yeast extract (CYE) agar
21
Q
- Haemophilus influenzae causes ocular infections
(pinkeye) and requires X and V factors in the
primary medium for growth. The subspecies
Haemophilus influenza (biogroup) aegyptius can
further be identified and differentiated by which
two tests?
A. Indole and xylose
B. Glucose and urease
C. Oxidase and catalase
D. ALA test and oxidase
A
A. Indole and xylose
22
Q
- Haemophilus species that require the V factor
(NAD) are easily recovered on which primary
agar plate?
A. Blood agar made with sheep red cells
B. Blood agar made with horse red cells
C. Chocolate agar
D. Xylose agar
A
C. Chocolate agar
23
Q
- Which of the following products is responsible
for satellite growth of Haemophilus spp. around
colonies of Staphylococcus and Neisseria spp. on
sheep blood agar?
A. NAD
B. Hemin
C. Indole
D. Oxidase
A
A. NAD
24
Q
- Which of the following plates should be used in
order to identify Haemophilus haemolyticus and
Haemophilus parahaemolyticus?
A. Sheep blood agar and chocolate agar
B. Horse blood agar and Mueller–Hinton agar with
X and V strips
C. Brain–heart infusion agar with sheep red cells
added
D. Chocolate agar and Mueller–Hinton agar with X
factor added
A
B. Horse blood agar and Mueller–Hinton agar with
X and V strips
25
Q
- The majority of Haemophilus influenzae infections
are caused by which of the following capsular
serotypes?
A. a
B. b
C. c
D. d
A
B. b
26
Q
- Which Haemophilus species is generally associated
with endocarditis?
A. H. influenzae
B. H. ducreyi
C. H. aphrophilus
D. H. haemolyticus
A
C. H. aphrophilus
27
Q
- Which Haemophilus species is difficult to isolate
and recover from genital ulcers and swollen lymph
nodes?
A. H. aphrophilus
B. H. ducreyi
C. H. haemolyticus
D. H. parahaemolyticus
A
B. H. ducreyi
28
Q
- Which of the following is a characteristic of strains
of Haemophilus influenzae that are resistant to
ampicillin?
A. Production of β-lactamase enzymes
B. Hydrolysis of chloramphenicol
C. Hydrolysis of urea
D. All of these options
A
A. Production of β-lactamase enzymes
29
Q
- A small, gram-negative coccobacillus recovered
from the CSF of a 2-year-old child gave the
following results:
Indole = +
Glucose = + (acid)
X requirement = +
V requirement = +
Urease = +
Lactose = Neg
Sucrose = Neg
Hemolysis = Neg
Which is the most likely identification?
A. Haemophilus parainfluenzae
B. Haemophilus influenzae
C. Haemophilus ducreyi
D. Haemophilus aphrophilus
A
B. Haemophilus influenzae
30
Q
- The δ-ALA test (for porphyrins) is a confirmatory
procedure for which test used for identification of
Haemophilus species?
A. X factor requirement
B. V factor requirement
C. Urease production
D. Indole production
A
A. X factor requirement
31
Q
- An elderly woman who cared for several domestic
cats was hospitalized with suspected cat-scratch
disease (CSD). Blood cultures appeared negative,
but a small, slightly curved pleomorphic
gram-negative bacillus grew on BHI agar (brain,
heart infusion agar with 5% horse or rabbit
blood). What is the most likely identification?
A. Bartonella spp.
B. Brucella spp.
C. Kingella spp.
D. Haemophilus spp
A
A. Bartonella spp.
32
Q
- A 5-year-old nonimmunized male with a persistent
cough, fever, and flulike symptoms was admitted to
the hospital. Nasopharyngeal swabs were cultured
on 15% blood, chocolate, Bordet–Genjou, and
Regan–Lowe (with 10% charcoal) agars. All media
grew a gram-negative coccobacillus. Carbohydrate
and biochemical tests were negative. What is the
most likely identification?
A. Haemophilus influenza
B. Bordetella pertussis
C. Haemophilus parainfluenzae
D. Bordetella bronchiseptica
A
B. Bordetella pertussis
33
Q
- A 29-year-old male who often hunted rabbits
and spent a lot of time in the woods was admitted
to the hospital with skin ulcers on his upper
extremities. At 48 hours, a small coccobacillus was
recovered from the aerobic blood culture bottle
only. The organism stained poorly with Gram
stain, but did stain with acridine orange. Cultures
taken from the ulcers did not grow on primary
media. What is the most likely identification?
A. Pseudomonas aeruginosa
B. Pseudomonas fluorescens
C. Chryseobacterium spp.
D. Francisella tularensis
A
D. Francisella tularensis
34
Q
- A neonate was readmitted to the hospital with
a diagnosis of meningitis. The CSF revealed
gram-negative straight rods. At 24 hours, the
organism grew on 5% sheep blood and chocolate
agars displaying a yellow pigment. On MacConkey
agar, it appeared as a non–lactose fermenter.
Colonies were oxidase, DNase, and gelatinase
positive, and oxidized glucose and mannitol.
What is the most likely identification?
A. Haemophilus influenza
B. Chryseobacterium meningosepticum
C. Stenotrophomonas maltophilia
D. Acinetobacter baumannii
A
B. Chryseobacterium meningosepticum
35
Q
- A 46-year-old dog warden was admitted to the
hospital with several puncture bite wounds
encountered while wrangling with a stray dog.
Culture at 48 hours produced small yellow
colonies on 5% sheep blood and chocolate agars in
10% CO2, but no growth on MacConkey agar.
Gram stain showed gram-negative curved,
fusiform rods. Colonies were oxidase and catalase
positive. What is the most likely identification?
A. Capnocytophaga canimorsus
B. Francisella tularensis
C. Legionella pneumophila
D. Pseudomonas aeruginosa
A
A. Capnocytophaga canimorsus
36
Q
- The HACEK group of organisms (Haemophilus
aphrophilus, Actinobacillus actinomycetemcomitans,
Cardiobacterium hominis, Eikenella corrodens, and
Kingella spp.) are all known for which type of
infection?
A. Urinary tract
B. Endocarditis
C. Pharyngitis
D. Tonsillitis
A
B. Endocarditis
37
Q
- A suspected case of Legionnaires’ disease was
noted on the request form for a culture and
sensitivity ordered on a sputum sample. The
patient was a 70-year-old male who presented with
a positive serological test for Legionella spp. What
is the most efficient way to confirm the infection
using the submitted sample?
A. Culture the sputum on MacConkey agar
B. Gram stain of the sputum
C. Acid-fast staining
D. Direct immunofluorescent microscopy
A
D. Direct immunofluorescent microscopy
