Microbiology: Enteric bugs - bacteria 5

Question 1

What is the presentation of EHEC?

Answer 1

Within 24 hours of eating contaminated food

Sudden onset of watery diarrhea –> bloody diarrhea. Can last up to 8 days

Question 2

How is EHEC contracted and who gets it?

Answer 2

Contracted from ground beef, bad milk, contaminated water

Think childcare centers

Question 3

What is the pathogenesis of EHEC?

Answer 3

EHEC binds to cell –> injects shigella-like toxin via type III secretion system –> Toxin cleaves 28s Ribosomal RNA –> Cell death

Question 4

How is EHEC diagnosed?

Answer 4

Culture: Gram- bacilli,
McConkey agar: White colonies
The only sorbital negative E. coli
RADT

Question 5

What is the Treatment for EHEC?

Answer 5

NO antibiotics ( may cause HUS)
Fluid replacement + blood transfusion + Temporary dialysis

Question 6

What are the microbiological characteristics of EHEC?

Answer 6

O157:H7
Shiga toxin (Stx) cleaves 28s RNA of ribosome
Type III secretion system

Question 7

What should be included in the DDx for EHEC?

Answer 7

Shigella
Salmonella
Campylobacter
EIEC
C. diff

Question 8

What is the presentation of ETEC?

Answer 8

Non-inflammatory high volume diarrhea

Question 9

What is the differential diagnosis for ETEC?

Answer 9

ETEC
V. cholerae
V. parahemolyticus

Question 10

What is the epidemiology of ETEC?

Answer 10

Leading cause of 3rd world diarrhea (travelers diarrhea)

Waterborne, foodborne, infants

Question 11

What is the pathogenesis of ETEC?

Answer 11

Contaminated food/water –> Colonizes SI via fimbrae –> Secretes LT + ST –> Secretory diarrhea

Question 12

What is the treatment for ETEC?

Answer 12

Oral rehydration therapy

Question 13

What is the microbiology of ETEC?

Answer 13

Lac-, non-motile
LT = increased cAMP –> increased CFTR
ST = Increased cGMP –> increased CFTR
Fimbrae and pedestal formation.

Question 14

What is the presentation of EIEC?

Answer 14

Watery diarrhea –> scant bloody diarrhea (within +/- 1 day)

Cramps, tenesmus, fever

Question 15

What is the DDx of EIEC?

Answer 15

EHEC
shigella
salmonella
campylobacter
C. diff

Question 16

What is the epidemiology of EIEC?

Answer 16

Travelers diarrhea (2nd to ETEC)
Human's are only reservoir

Question 17

What is the pathogenesis of EIEC?

Answer 17

3rd world person-person contact –> penetrates enterocytes –> multiply within enterocytes –> Actin tail, propulsion, shigella toxin –> cell death

Question 18

How is EIEC diagnosed?

Answer 18

Culture: Gram- bacilli, Lac-, No decarboxylation of lysine. Non-motile

Sorbital+

Question 19

What is the presentation of EPEC?

Answer 19

Profuse watery diarrhea +/- bloody diarrhea, +/- inflammation, no fever.

Question 20

What is the DDx for EPEC?

Answer 20

Any infectious or inflammatory diarrhea.

Question 21

What is the epidemiology of EPEC?

Answer 21

Leading cause of infantile diarrea

contracted from contaminated water/meat

Question 22

What is the pathogenesis of EPEC?

Answer 22

Consumption of contaminated water/food –> moderately invasive –> Induces inflammatory response –> Intracellular replication –> decreased normal signaling transduction –> Loss of microvilli –> Osmotic diarrhea

Question 23

How is EPED diagnosed?

Answer 23

Culture: Gram- bacilli, Lac-

Question 24

What is the treatment for EPEC?

Answer 24

Oral rehydration therapy

Question 25

What are the microbiological characteristics of EPEC?

Answer 25

Adherence factor = localized binding
Intimin adherence
LEE and pedestal formation.