Deck 35: Gastrointestinal System

Question 1

In the gastrointestinal system, the majority of the bacterial actions that are part of the digestive process occur in the

A) stomach.
B) small intestine.
C) appendix.
D) large intestine.

Answer 1

large intestine.

Question 2

Which of the following organisms are usually considered normal intestinal flora but may become clinically significant when normal GI flora is disturbed due to antibiotic use.

A) Candida albicans
B) Pseudomonas aeruginosa
C) Enterococcus spp.
D) a and b
E) a and c

Answer 2

a and b

Question 3

A high dose of organism inoculum is required to establish gastrointestinal disease for all of the following organisms except

A) Shigella spp.
B) Campylobacter spp.
C) Vibrio cholerae.
D) Salmonella spp.

Answer 3

Shigella spp.

Question 4

Which of the following organisms can be normal flora and only causes disease when it produces toxin in the gastrointestinal tract?

A) Staphylococcus aureus
B) Clostridium difficile
C) Bacillus cereus
D) a, b and c
E) a and b

Question 5

A large cruise ship must end its current voyage early due to an outbreak of nausea, vomiting, and diarrhea among its passengers. Your laboratory is asked to help process stool samples to determine the causative agent of the outbreak. You suspect the causative agent to be

A) rotavirus.
B) Salmonella spp.
C) norovirus.
D) Campylobacter jejuni.

Question 6

A 4-year-old female develops diarrhea, and her mother takes her to the pediatrician. The child attends daycare five days a week while the mother works. The family had recently returned from a camping trip where the little girl spoke of catching turtles and lizards. An image of the HE agar plate of the child's stool culture is provided.
Source: CDC
Given this information , which of the following apply to this organism?

A) a non-lactose fermenter.
B) lysine decarboxylase negative.
C) a swarming colony on blood agar.
D) spot indole positive.

Question 7

A stool culture was received from a 34-year-old male who is experiencing diarrhea after a family reunion picnic. The food served included hot dogs, hamburgers, fried chicken, potato salad, baked beans, and various desserts. The image provided shows the Hektoen-enteric agar growth from his culture.
Source: CDC
Based on these results, your next step in the workup of this stool culture is to

A) perform testing to detect shiga toxin.
B) disregard it as normal flora.
C) perform Shigella serotyping.
D) identify using saline as the inoculum suspension.

Question 8

After a visit to Chicago over Christmas, a couple returns to St. Louis with nausea, diarrhea, and cramping in the lower right quadrant of their abdomens. They admitted to indulging in a family favorite of chitterlings over the holidays. The routine stool culture of both individuals provided the same results:
BAP: all colonies present are oxidase negative and no beta-hemolytic colonies observed
MAC: lactose fermenters and oxidase negative, non-lactose fermenters HE: yellow colonies
PEA: no suspicious colonies
Campy blood agar: no growth
Based on the patient history, the original orders also requested the stool specimens be cultured for an additional enteric pathogen. The processing technician noted the request and added one
Additional agar plate to the routine stool culture media. The additional agar demonstrates the potential enteric pathogen as _________ colonies.

A) Red centered and clear edged
B) Yellow
C) Colorless
D) Green metallic

Question 9

A stool agar plate incubated at 42°C in an atmosphere of 5% O₂, 10% CO₂, and 85% N₂ grew as a tan colony that tends to follow the streak lines. An image of the Gram stain results of the colonies is provided.
Source: CDC
You would expect this organism to be

A) oxidase positive.
B) catalase positive.
C) hippurate hydrolysis negative.
D) a and b.
E) all of the above.

Question 10

The blood agar plate of a stool culture is screened using the oxidase test. It is determined that a large, wet, gray colony is oxidase positive. Based on this result, the next agar plate you should examine is the

A) XLD.
B) MAC.
C) HE.
D) campy blood agar.

Question 11

A 22-year-old male presents to his physician with vomiting and severe, watery diarrhea after spring break in New Orleans, LA. Given this patient history, what additional enteric medium should be added to the routine stool culture?

A) CIN
B) SMAC
C) TCBS
D) CCFA

Question 12

At 4 pm, a physician requests that you add a culture for Clostridium difficile to a routine stool culture he wrote orders for at 9 am. You will

A) comply with his request.
B) offer to perform toxin detection instead.
C) offer to send the stool to the state public health laboratory.
D) request a new specimen due to the delay.

Question 13

An oxidase negative, non-lactose fermenter isolated from the stool culture of a 3-year-old female with bloody diarrhea. The organism proves to be:
If it serotypes as a group D, you would identify the organism as

A) Salmonella typhi.
B) Shigella dysenteriae.
C) Shigella sonnei.
D) The serotype must be repeated after boiling the organism suspension.

Question 14

Based on the Gram stain image of a fecal specimen provided, determine the probable pathogenic mechanism responsible if the diarrhea present is due to an enteric bacterial pathogen.
Source: CDC

A) Enterotoxin production
B) Cytotoxin production
C) Neurotoxin production
D) Adherence

Question 15

The disease caused by Salmonella typhi differs from that caused by other Salmonella spp. because it

A) produces a powerful enterotoxin.
B) penetrates the intestinal cells to spread to the blood.
C) produces a lethal cytotoxin that causes cell death.
D) causes acute mesenteric lymphadenitis.

Question 16

The disease mechanism of enterotoxigenic E. coli closely resembles that of

A) Vibrio cholerae.
B) Shigella spp.
C) Salmonella typhi.
D) Campylobacter jejuni.

Question 17

E. coli O157:H7 is one example of an ______________________ strain.

A) enteroinvasive
B) enteropathogenic
C) enterotoxigenic
D) enterohemorrhagic

Question 18

The most important initial treatment for diarrhea is

A) replacement of fluids and electroloytes.
B) use of bismuth subsalicylate.
C) antibiotics.
D) probiotics.