Enterobacteriaceae I 9/3/15

Question 1

What are the 4 unvarying characteristics of the family Enterobacteriaceae?

Answer 1

1. Good growth overnight: Fac. anaerobes
2. Ferment glucose; Reduce nitrAte to nitrIte
3. Oxidase NEGATIVE
4. Gram NEGATIVE rods: short and fat

Question 2

What are some clinical syndromes associated with E. coli?

Answer 2

***UTI ***Meningitis in neonates ***Gastroenteritis -Wound infections -Pneumonia in hospitalized patients -Sepsis

Question 3

Name the 5 genera of Enterobacteriaceae that can cause gastrointestinal disease.

Answer 3

1. Escherichieae
2. Shigella
3. Salmonella
4. Edwardsiella
5. Yersinia

Question 4

What signs and symptoms are produced by Enterotoxigenic E. coli (ETEC)?

Answer 4

• Secretory/profuse, watery diarrhea (Traveler’s diarrhea) -Sometimes with cramps, dehydration and vomiting
• THINK: eTec = Travelers

Question 5

Describe the signs and symptoms of Enteropathogenic E. coli (EPEC).

Answer 5

• THINK: ePec = Pediatric diarrhea (infants)
• Low-grade fever
• Malaise
• Vomiting
• Diarrhea (with lots of mucus, NO Blood)

Question 6

What strain of bacteria is associated with the following signs and symptoms?

• Inflammatory diarrhea (dysentery)
• Fever
• Colitis
• Urgency and tenesmus
• Blood, mucus and leukocytes in stool

Answer 6

Enteroinvasive E. coli (EIEC)

THINK: eIec = inflammatory

Question 7

What two strains of bacteria are associated with the following signs and symptoms?

• Bloody diarrhea without WBCs
• No fever
• Abdominal pain
• May progress to hemolytic uremic syndrome (HUS)

Answer 7

Enterohemorrhagic E. coli (EHEC) and Shiga Toxin producing E. coli (STEC)

• Primarily caused by E. coli O157:H7
• THINK: eHec = Hemorrhaging without the inflammation

Question 8

What are the signs and symptoms of Enteroaggregative E. coli (EAggEC)?

Answer 8

• Watery diarrhea with blood and mucus
• Vomiting
• Dehydration
• Abdominal pain sometimes

Question 9

List the symptoms that defines hemolytic uremic syndrome (HUS).

Answer 9

• Acute renal failure
• Thrombocytopenia
• Hemolytic anemia
• Caused primarily by E. coli O157 (STEC)

Question 10

Describe the reservoir of Shiga Toxin producing E. coli.

Answer 10

• Feces of animals:
• healthy cattle (esp. dairy)
• sheep
• deer

Question 11

What is the mode of transmission of STEC?

Answer 11

• Contaminated food or water: GROUND BEEF
• Direct contact with infected patient

Question 12

What strain of bacteria causes the following clinical presentation?

• Bloody and nonbloody diarrhea
• HUS
• Hemorrhagic Colitis

Answer 12

STEC

Question 13

Describe the method of lab diagnosis of Shiga toxin producing E. coli.

Answer 13

• Antigens: Shiga toxin or O157 antigen (LPS)
• Direct fecal specimen
• Enriched broth culture (more sensitive)

-Multiplex PCR (newest/fastest)

Question 14

What are the treatment options for disease caused by STEC?

Answer 14

• Oral rehydration: Gatorade/Pedialyte
• Supportive care
• Monitoring kidney function
• Dialysis (for HUS and renal failure)
• NO ANTIBIOTICS
• NO ANTI-MOTILITY AGENTS