(Harr) IV. Miscellaneous and Fastidious Gram-Negative Rods Flashcards
(24 cards)
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
C. TCBS agar
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.
B. Vibrio parahaemolyticus
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
B. Campylobacter jejuni
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. 5% O2, 10% CO2, and 85% N2
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
D. Urease, nitrate, and hippurate hydrolysis
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
C. Oxidase
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. Oxidase
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. Actinobacillus
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
B. DNase and VP
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. Eikenella corrodens
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
B. Indole
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. Sheep blood agar
Kingella kingae is usually associated with which type of infection?
A. Middle ear
B. Endocarditis
C. Meningitis
D. Urogenital
B. Endocarditis
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.
C. Capnocytophaga spp.
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
D. Bordet–Gengou agar
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.
B. Pasteurella spp.
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
A. Biphasic Castenada bottles with Brucella broth
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. Basic fuchsin and thionin
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
C. Cysteine and cystine
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
D. Buffered charcoal–yeast extract (CYE) agar
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
Microbiology/Select methods/
A. Indole and xylose
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
C. Chocolate agar
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. NAD
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
B. Horse blood agar and Mueller–Hinton agar with X and V strips
