Deck 23: Vibrio, Aeromonas, Plesiomonas, Campylobacter, Helicobacter, and Chromobacterium

Question 1

A physician suspects his patient has Helicobacter pylori. To confirm the diagnosis, he will submit a

A) stool specimen.
B) blood culture.
C) gastric biopsy.
D) swab of the infected wound site.

Answer 1

gastric biopsy.

Question 2

Which of the following scenarios indicates the potential for the isolation of Vibrio vulnificus?

A) A fish hook injury on the hand of a 58-year-old male acquired while on vacation in the Gulf of Mexico.
B) A 24-year-old female experiencing massive diarrhea after visiting New Delhi for missionary work.
C) A 17-year-old female experiencing diarrhea after eating undercooked chicken at a family picnic.
D) A foot wound from a 7-year-old male acquired while catching frogs in a freshwater stream.

Answer 2

A fish hook injury on the hand of a 58-year-old male acquired while on vacation in the Gulf of Mexico.

Question 3

Alkaline peptone water is an ideal transportation medium for

A) Campylobacter jejuni.
B) Aeromonas hydrophila.
C) Vibrio cholerae.
D) Helicobacter pylori.

Answer 3

Vibrio cholerae.

Question 4

The pathogenesis of Vibrio cholerae is related to its ability to

A) invade tissue and produce an exotoxin.
B) produce an ammonia cloud for protection.
C) invade the mucous membranes of the intestine.
D) produce a powerful enterotoxin.

Question 5

Which of the following environments or atmospheres is required for the isolation of a gram-negative rod that is a stool pathogen and oxidase positive, catalase positive, and able to hydrolyze hippurate?

A) Halophilic
B) Capnophlic and microaerophilic
C) Facultative anaerobic
D) Ambient air

Question 6

Which of the following oxidase-positive, gram-negative rods can be differentiated from Vibrio cholerae based on its inability to grow on thiosulfate citrate bile salts agar?

A) Non-lactose fermenter that is also K/A on TSI, arginine negative, and resistant to 10 µg O/129 but susceptible to 150 µg O/129
B) Lactose fermenter that is also A/A on TSI, arginine negative, and susceptible to both 10 µg and 150 µg O/129
C) Lactose fermenter that is also A/A on TSI, arginine positive, and resistant to both 10 µg and 150 µg O/129
D) Non-lactose fermenter that is also A/A on TSI, arginine negative, and susceptible to both 10 µg and 150 µg O/129

Question 7

Which of the following tests can be used to rapidly identify Helicobacter pylori?

A) Oxidase
B) Spot indole
C) Catalase
D) Urease

Question 8

All of the following tests can be used to differentiate Aeromonas hydrophila and Plesiomonas shigelloides except

A) indole.
B) ornithine.
C) gelatinase.
D) DNase.

Question 9

Aeromonas hydrophila, Plesiomonas shigelloides, and Chromobacterium violaceum share all of the following characteristics except

A) transmitted by contact with freshwater.
B) indole production.
C) oxidase production.
D) arginine positive.

Question 10

Small comma-shaped, oxidase-positive, gram-negative rods that are susceptible to O/129 and string test positive is characteristic for an organism that

A) is part of the normal gut flora of leeches.
B) is able to grow at 42°C.
C) causes the production of rice water stools.
D) causes peptic ulcers.

Question 11

Which of the following Vibrio species does not require saline for growth?

A) V. alginolyticus
B) V. vulnificus
C) V. parahaemolyticus
D) V. cholerae

Question 12

Campylobacter jejuni is unique in that it will grow, with the appropriate atmosphere, at

A) 4°C.
B) 35°C.
C) 42°C.
D) all of the above.
E) a and c.

Question 13

A gram-negative rod is isolated from the bronchial aspirate of an individual who inhaled a minnow while swimming at Lake of the Ozarks in central Missouri. The organism is oxidase positive. Which of the following organism identifications is least likely for this isolate?

A) E. coli
B) Aeromonas hydrophila
C) Plesiomonas shigelloides
D) Pseudomonas aeruginosa

Question 14

A dark pigmented colony is isolated from the leg wound of a fisherman from Florida. The gram-negative rod grows on sheep blood and MacConkey agars. The organism provides the following reactions:
$\begin{array}{lll}\text {TSI: K/ A } &\text {Indole: no color change }&\text {Lysine: no color change}\\\text {1 \% NaCL : no growth}&\text { Arginine: purple}&\text {Ornithine: no color change}\\\text {DNase: pink halo around the area of organism inoculum}\end{array}$
The microbiologist cannot read the oxidase reaction due to the dark pigment. What can he do to help achieve a valid oxidase reaction?

A) Perform a modified oxidase test
B) Grow the organism under anaerobic conditions and retest
C) The oxidase test is not necessary for the identification of this organism
D) Grow the organism on a non-nutrient agar and retest

Question 15

A 22-year-old male has recently adopted an Akita puppy that develops diarrhea soon after he takes it home. He soon develops bloody diarrhea and visits his physician. The doctor submits a stool for routine culture and ova and parasite examination. The O & P examination was negative. The routine culture reveals no Salmonella, Shigella, or verotoxin producing E. coli. On special medium, at a unique temperature and atmosphere, a slightly spreading, gray, flat colony is observed. A Gram stain of the colony provides gram-negative rods that appear "S" shaped. Which of the following tests can be used to screen and presumptively identify this stool pathogen?

A) Catalase and oxidase
B) Hippurate hydrolysis
C) Indoxyl acetate
D) All of the above

Question 16

Helicobacter pylori is easily identified from a gastric biopsy based on which of the following tests?

A) Oxidase
B) Gram stain
C) Urease
D) H₂S production

Question 17

A stool culture reveals an oxidase-positive, non-lactose fermenting colony. A suspension of the organism was made in sterile distilled water and used to inoculate a commercial identification strip that did not demonstrate any positive reactions after incubation. The microbiologist then set up traditional biochemical tube tests and the results were still negative. What is the next step in the identification process?

A) Perform halotolerance testing
B) Reincubate the identification tubes in CO₂
C) Perform a string test
D) Perform serologic testing using O1 and O139 antisera

Question 18

If you suspect an isolate to be Vibrio spp., which of the following tests would you be least likely use as part of the identification scheme due to its low sensitivity and specificity?

A) O1 and O139 antisera
B) O/129 susceptibility
C) String test
D) TCBS growth

Question 19

Each of the following tests can be used to monitor the effectiveness of therapy against Helicobacter pylori except

A) gastric biopsy.
B) urea breath test.
C) serology.
D) b and c.
E) a and b.

Question 20

Which of the following individuals could potentially have the worst outcome if his or her described infection is due to Vibrio vulnificus?

A) 47-year-old on vacation in Biloxi, MS. who develops gastroenteritis
B) 58-year-old liver transplant recipient with septicemia
C) 69-year-old alcoholic deep sea fisherman with an infected hand wound
D) 21-year-old surfer with an infected leg wound