Enteric Bac 1

Question 1

What is the gram stain of Shigella?

Answer 1

Gram neg rod

Question 2

Does shigella need a high dose or low dose to infect?

Answer 2

Low dose

Question 3

What complications are pts at risk of developing with shigella infection?

Answer 3

Reactive arthritis–reiter’s syndrome

Hemolytic-Uremic Syndrome–HUS

Question 4

Pts who develop reactive arthritis as a complication of shigella infection are positive for?

Answer 4

HLA-B27

Question 5

What does the plasmid of Shigella carry in order to parasitize enough iron to grow to large numbers?

Answer 5

Genes for siderophores–iron-chelating molecules

Question 6

Where does the shigella enter the ileum and colon?

Answer 6

M cells of Peyer’s patch

Uses a type III secretion system

Question 7

What is the type 3 secretion system virulence factor of shigella involved in?

Answer 7

Injects M cell–enhances bacterial translocation and decreases inflammatory response

Question 8

What is the IcsA virulence factor of shigella involved in?

Answer 8

Bacterial use of host actin to cross into neighboring cells directly

Question 9

What is the IpaB virulence factor of shigella involved in?

Answer 9

Induces macrophage apoptosis–> no phagocytosis, increases inflammatory response

Question 10

When does HUS begin?

Answer 10

When shiga toxin escapes into blood stream

Question 11

What is seen on PE of pt with shigella infection?

Answer 11

Fever
Dehydration
Severe HA
Progression from watery to bloody diarrhea

Question 12

What is seen on the bloodwork of a pt with HUS from shigella?

Answer 12

Schistocytes
Decreased platelets
Increased PMNs
Increased lactate dehydrogenase

Question 13

If neutrophils are present on methylene blue stain of fecal sample then whats the ddx?

Answer 13

Shigella
Salmonella
Campylobacter

Question 14

If neutrophils are NOT present on methylene blue stain of fecal sample then whats the ddx?

Answer 14

V. cholerae
E. coli
C. perfringens

Question 15

Does Abx treatment in shigella increase or decrease HUS risk?

Answer 15

Decreases HUS risk–opposite of EHEC

Question 16

What is the gram stain for E. coli?

Answer 16

Gram negative rod

Question 17

What virulence factor is present in E. coli that allows for adherence to host cell?

Answer 17

Fimbriae

Question 18

What virulence factor is present with E. coli allowing molecules to force cell to form actin bundle, causing inflammation?

Answer 18

Type 3 and/or 4 secretion systems

Question 19

What virulence factor is present with E. coli that allows actin-based cell-to-cell motility just like in shigella?

Answer 19

IcsA

Question 20

What is the pathogenesis of gastroenteritis caused by E. coli?

Answer 20

Watery diarrhea–bacteria use timbre to attach to gut lining–attach to jejunum and ileum

LT–Enterotoxins force host cells to release fluids, potassium and Chloride

Question 21

What is the pathogenesis of bloody gastroenteritis caused by e. coli?

Answer 21

EHEC attach to the mucosal epithelial cells of the colon

Lysogenic phage STX encodes Shiga toxin–Becomes active in the gut cells, shuts down protein synthesis and destroys some

Causes inflammation and bloody diarrhea

Toxin may reach blood stream causing HUS

Question 22

What is seen with HUS caused by E. coli?

Answer 22

Fever
Dehydration
Thrombocytopenia
Uremia requiring dialysis
Blood smear--Schistocytes, low platelets, High PMNs, elevated serum level of lactate dehydrogenase

Question 23

If Abx are used for tx of enterohemorrhagic diarrhea caused by E. coli what is the pt at risk of developing?

Answer 23

HUS–opposite of shigella

Question 24

What is seen with staph aureus, bacillus cereus food poisoning and food borne botulism?

Answer 24

Rapid onset—HOURS, not days