Gram Negative Rods

Question 1

Oral-Fecal transmission (Four F’s)

Answer 1

Food (& water), Feces, Fingers, Flies

Question 2

Vibrio cholerae epidemiology

Answer 2

Endemic in SE Asia

Question 3

Cholera toxin-Action

Answer 3

cAMP constantly activates CFTR
High salt leads to osmotic flow of water which leads to watery diarrhea

Question 4

Vibrio cholerae disease

Answer 4

Massive diarrhea
Death from hypovolemia
Fluid replacement + antibiotics

Question 5

Non-cholera vibrios

Answer 5

Common in natural waters
Diarrhea from raw fish
Wound/soft tissue infections

Question 6

3 types of E.coli

Answer 6

Enterotoxigenic E.coli
Enteropathogenic E. coli
Shiga toxin producing E.coli

Question 7

Enterotoxigenic E.coli (ETEC)

Answer 7

Most adults immune to local strain
Two exotoxins (Labile Toxin and Stable Toxin)
Elevated cAMP produce diarrhea

Question 8

Enteropathogenic E.coli (EPEC)

Answer 8

Attaches and injects into epithelial cells (type III secretion system)
Pedestal that cups bacteria produced

Question 9

Shigella

Answer 9

Infect humans only
Very infectious
Genetically identical to E.coli

Question 10

Shigella symptoms

Answer 10

Frequent painful bloody stool. contains wbc, mucus
Abdominal cramps

Question 11

Shigella species

Answer 11

S. dysenteriae (most virulent, least common)
S. sonnei (least virulent, most common)

Question 12

Shigella virulence

Answer 12

Invade and kill cells of intestinal mucosa