Deck 33: Campylobacter, Arcobacter, and Helicobacter

Question 1

Campylobacter spp.can sometimes be detected by direct Gram-stain examination of fecal sample, which would reveal many:

A) large, faintly staining gram-negative bacilli.
B) small curved or seagull-winged gram-negative bacilli.
C) small gram-negative coccobacilli.
D) plump, faintly staining gram-negative bacilli.

Answer 1

B
Because of their characteristic microscopic morphologic features, that is, their small, curved or seagull-winged, faintly staining, gram-negative rods, Campylobacter spp.can sometimes be detected by direct Gram-stain examination of a stool sample.

Question 2

Campylobacter jejuni subsp.jejuni grows best at what conditions?

A) 37º C under microaerobic conditions
B) 37º C under anaerobic conditions
C) 42º C under microaerobic conditions
D) 42º C under anaerobic conditions

Answer 2

C
C.jejuni subsp.jejuni grows best at 42º C in microaerobic conditions.The atmosphere can be generated in several ways, including commercially produced, gas-generating envelopes to be used with plastic bags or jars.

Question 3

Curved, microaerophilic, gram-negative rods, with most species having strong urease activity and the majority of which colonize mammalian stomachs or intestines, describe which group of bacteria?

A) Campylobacter
B) Helicobacter
C) Arcobacter
D) Enterobacter

Answer 3

B
In 1983, spiral-shaped organisms resembling campylobacteria were isolated from the human stomach; these organisms were named Campylobacter pylori.On the basis of many studies, the genus Helicobacter was established in 1989, and C.pylori were renamed Helicobacter pylori.At least 32 species are now included in this genus, the majority of which colonize mammalian stomachs or intestines.The genus Helicobacter consists mostly of curved, microaerophilic, gram-negative rods, with most species having strong urease activity.

Question 4

Which of the following genes may attribute to the virulence of Helicobacter pylori by encoding for outer membrane proteins that mediate adherence to a specific blood group antigen on the surface of gastric epithelial cells?

A) babA
B) iceA
C) cagA
D) vacA

Question 5

Virulence determinants of Helicobacter pylori include:

A) proteases.
B) urease enzyme.
C) hemolysins.
D) exotoxins.

Question 6

Ensuring that all foods derived from animal sources are thoroughly cooked, all milk is pasteurized, and all drinking water is chlorinated are ways to avoid becoming infected with:

A) Helicobacter.
B) Arcobacter.
C) Enterobacter.
D) Campylobacter.

Question 7

A gram-negative, spiral-shaped organism is isolated from a stool sample that was hippurate-positive, catalase-positive, susceptible to nalidixic acid, and resistant to cephalothin.The organism can be identified as:

A) Campylobacter coli.
B) C. jejuni subsp. doylei.
C) C. jejuni subsp. jejuni.
D) C. fetus subsp. fetus.

Question 8

The majority of human infections with Campylobacter species are caused by:

A) direct contact with carriers of the bacterium.
B) contamination of food, milk, or water with animal feces.
C) multiplication of the organism in food products.
D) direct contact with persons infected with the bacterium.

Question 9

Which organisms should be used to perform quality control on hippurate reagent?

A) Campylobacter coli and C. concisus
B) C. curvus and C. hyointestinalis
C) C. jejuni subsp. jejuni and C. jejuni subsp. doylei
D) C. jejuni subsp. jejuni and C. coli

Question 10

Antimicrobial therapy for Helicobacter pylori infection consists of:

A) penicillin, gentamycin, and imipenem.
B) clindamycin, ceftriazone, and carbapenem.
C) metronidazole, bismuth salt, and tetracycline.
D) azithromycin alone.