Campylobacter Practical Medical Microbiology Lab

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Questions and Answers

What is the optimal temperature for incubating modified Skirrow's medium to recover Campylobacter spp. from stool specimens?

37°C
45°C
42°C (correct)
50°C

What is the characteristic shape of Helicobacter spp.?

Straight rods
Spiral rods
Branched rods
Curved rods (correct)

Which of the following is a characteristic of Campylobacter spp. colonies?

Colorless and dry
Gray to pinkish or yellowish gray and slightly mucoid (correct)
Red and shiny
Black and rough

What is the purpose of using selective media in culturing Campylobacter spp. from stool?

To inhibit the growth of other bacteria (D) Signup and view all the answers

What is the typical duration of incubation required for the growth of Campylobacter spp. in blood culture media?

2 weeks (B) Signup and view all the answers

What is the characteristic motility of Campylobacter spp. in a wet preparation?

Darting motility (C) Signup and view all the answers

What percentage of oxygen is suitable for the growth of Campylobacter spp.?

5% to 10% O2 (C) Signup and view all the answers

Which of the following animals is NOT a common inhabitant of Campylobacter spp.?

Honey bees (D) Signup and view all the answers

What is the most common syndrome associated with Campylobacter spp. infection in humans?

Gastroenteritis (C) Signup and view all the answers

What is the purpose of using Cary-Blair transport medium for stool specimens?

To preserve the viability of the organisms during transport (C) Signup and view all the answers

What is the characteristic microscopic morphology of Campylobacter spp.?

Small, curved or seagull-winged, faintly staining, gram-negative rods (A) Signup and view all the answers

What is the recommended storage temperature for specimens received in transport medium?

4°C (A) Signup and view all the answers

What is Helicobacter pylori associated with?

All of the mentioned diseases (D) Signup and view all the answers

What is the purpose of adding 0.1% basic fuchsin counterstain to Gram-stained squash preparations of biopsy material?

To enhance the morphology of the bacteria (A) Signup and view all the answers

Why is it necessary to place tissue biopsy material into transport media like Stuart's transport medium?

To prevent drying of the tissue (C) Signup and view all the answers

What is the purpose of the urease breath test?

To detect the presence of H. pylori urease (C) Signup and view all the answers

How does the urease test work?

The urease splits the urea, yielding a color change in the medium (D) Signup and view all the answers

What is the significance of a color change in the urease test medium?

It indicates the presence of H. pylori (A) Signup and view all the answers

What is the main product of urea hydrolysis by H. pylori?

Ammonia and CO2 (B) Signup and view all the answers

What is the purpose of detecting H. pylori antigen in stool specimens?

To monitor treatment response (C) Signup and view all the answers

What type of agar media is commonly used for the cultivation of H. pylori from tissue biopsy specimens?

Chocolate agar (C) Signup and view all the answers

What is the required environment for incubating Helicobacter spp. cultures?

Humidified, 5% to 10% O2 environment (D) Signup and view all the answers

How long may it take for H. pylori colonies to become visible on agar media?

4 to 7 days (A) Signup and view all the answers

What is the purpose of culturing H. pylori from biopsy specimens?

To assess susceptibility patterns (A) Signup and view all the answers

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Study Notes

• Campylobacter spp. can be detected by direct gram stain examination of stool, and molecular assays based on polymerase chain reaction (PCR). • Stool culture requires selective media and optimum incubation conditions, with Modified Skirrow’s medium being an example, and incubation at 42°C under microaerophilic conditions for 72 hours. • Blood culture media can also be used to detect Campylobacter spp. that cause septicemia, but may require up to 2 weeks for growth to be detected. • Characteristic colonies are gray to pinkish or yellowish gray, slightly mucoid, and may exhibit a tailing effect along the streak line. • A wet preparation of the organism in broth can be examined for characteristic darting motility and curved morphology on Gram stain. • Almost all pathogenic Campylobacter spp. are oxidase positive and catalase positive. • The genus Helicobacter consists of curved, microaerophilic, gram-negative rods, with most species having strong urease activity. • Nine Helicobacter spp. have been isolated from humans, with H. pylori, H. cinaedi, and H. fennelliae being the most significant human pathogens. • H. pylori is associated with antral gastritis, duodenal (peptic) ulcer disease, gastric ulcers, and gastric cancer. • Helicobacter infections are usually identified by non-culture methods, such as squash preparations of biopsy material, Gram-stained with good results. • Urea breath tests can be used to detect H. pylori, relying on the presence of H. pylori urease. • Fecal antigen detection and molecular methods can also be used to directly detect H. pylori. • Cultivation of Helicobacter spp. requires selective media, such as Campy-CVA, and incubation up to 1 week in a humidified, 5% to 10% O2 environment, at 35° to 37° C.

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