Enterobacteriaceae PART2

Question 1

Habitat and most common infection involving E. coli

Answer 1

• Large bowel (#1)

- Urinary Tract Infection (#1 most common cause), gastroenteritis

Question 2

Habitat and most common infection involving Shigella

Answer 2

• NOT normal flora (#1) / always pathogenic

- penetrate epithelial cells of intestinal mucosa (blood, mucous, leukocytes)

Question 3

Habitat and most common infection involving Salmonella

Answer 3

• NOT normal flora (#2)

- Gastroenteritis (animals) and Septicemia

Question 4

Habitat and most common infection involving Klebsiella pneumoniae

Answer 4

• Bowel (#2)

- pneumonia (“current-jelly”) and nosocomial infections

Question 5

Habitat and most common infection involving Citrobacter

Answer 5

• GI?

- variety of infections, primarily urinary tract infections

Question 6

Habitat and most common infection involving Serratia

Answer 6

• GI, also respiratory flora

- Formerly strictly saprophytic now major nosocomial problem

Question 7

Habitat and most common infection involving Enterobacter

Answer 7

• GI?

- Variety of infections, esp. UTI

Question 8

Habitat and most common infection involving Proteus and Morganella

Answer 8

• GI?

- UTI…triple phosphate (struvite) crystals, renal stones

Question 9

Habitat and most common infection involving Yersinia

Answer 9

• Bubonic (lymph), pneumonic (lungs), septicemic (blood)

- Agent of the plague

Question 10

Major source of infection for Enterohemorrhagic E. coli causing gastroenteritis

Answer 10

Hamburger, fruits, vegetables, water(pools), etc

Question 11

Major source of infection for Salmonella causing gastroenteritis

Answer 11

Animals (chicken, turtles, iguanas ect), food, water

Question 12

Major source of infection for causing gastroenteritis

Answer 12

?

Question 13

Major source of infection for causing gastroenteritis

Answer 13

?

Question 14

Major source of infection for Yersinia pestis

Answer 14

• endemic in rodents and transmitted by insect vector, domestic cats to humans

Question 15

Factors contributing to pathogenicity of EPEC and disease caused

Answer 15

Enteropathogenic E. coli

• due to organism’s ability to adhere to cells in small intestine
• Infant diarrhea

Question 16

Factors contributing to pathogenicity of ETEC and disease caused

Answer 16

Enterotoxigenic E. coli

• due to toxins (Heat labile toxin and Heat stable toxin)
• Traveler’s Diarrhea (Montezuma’s Revenge)

Question 17

Factors contributing to pathogenicity of EIEC and disease caused

Answer 17

Enteroinvasive E. coli

• due to ability to invade into cucosal cells of intestine not through to blood
• Similar to Shigella (no specific disease caused)

Question 18

Factors contributing to pathogenicity of STEC, EHEC, VTEC and disease caused

Answer 18

Shiga Toxin, Enterohemorrhagic E. coli, Verotoxin

• due to cytotoxins (verotoxins, and “shiga-like” toxins)
• Leading cause of acute renal failure in children

Question 19

Formulate an approach for isolating/ identifying E. coli (O157:H7) in stool cultures

• media?
• biochemical recommendations?
• typing recommendations?

Answer 19

(not sure of this answer but I think its important to know??)

• use sorbitol MacConkey Agar (will be sorbitol neg)
• run a MUG tes (will be MUG neg)

Question 20

Applications and advantages of shiga toxin testing on stool specimens

Answer 20

• some sorbitol positive STEC strains identified (would be missed by culture)
• assay will detect serotypes other than O157

Question 21

Compare and contrast the pathogenic mechanism involved in E. coli, Shigella, and Salmonellas gastroenteritis

Question 22

Typhoid Fever

• recommended type of specimen
• characteristics of the disease
• specific characteristics for identification of pathogens

Answer 22

• test positive in blood cultures
• Man only host, invasive, high fever, carriers harbor in gallbladder
• Serotyping required for identification: it is positive with Vi and group D antisera (may have to boil to get rxn with group D antisera)

Question 23

most common enteric agent of infection

- Urinary tract

Answer 23

E. coli

Question 24

most common enteric agent of infection

-abdominal wound

Answer 24

*

Question 25

most common enteric agent of infection | -newborn meningitis

Answer 25

*

Question 26

most common enteric agent of infection | - gastroenteritis

Answer 26

Salmonella

Question 27

most common enteric agent of infection | -HUS

Answer 27

Enterohemorrhagic E. Coli (STEC, EHEC, VTEC)

Question 28

most common enteric agent of infection | - pneumonia

Answer 28

Klebsiella pneumoniae

Question 29

most common enteric agent of infection | - typhoid fever

Answer 29

Salmonella Typhi

Question 30

most common enteric agent of infection | - plague

Answer 30

Yersinia pestis

Question 31

Name three Enterobacteriaceae that are ALWAYS considered pathogens, regardless of specimen site

Answer 31

Shigella, Salmonella