Microbiology: Enteric Bugs-Bacteria

Question 1

What are the microbiological characteristics of H. pylori?

Answer 1

Slender curved Gram negative rod
Microaerophilic

Similar to campylobacter

Question 2

What are the virulence factors of H. pylori?

Answer 2

1. Urease (buffers H+)
2. Vacuolating cytotoxin (from PAI)
3. Cytotoxin associated Protein (CagA)
4. Pilli

Question 3

In what populations is H. pylori infection most common?

Answer 3

Elderly and those of low socioeconomic status.

Question 4

What is the Pathogenesis of H. pylori infection?

Answer 4

fecal-oral transmission –> bacteria grow in stomach via urease –> Immune system cannot remove H. pylori b/c non-invasive –> Immune mediated damage.

Question 5

What diseases are caused by H. pylori?

Answer 5

Duodenal ulcers (90%)
Gastric ulcers (70%)
Gastric adenocarcinoma/lymphoma

Question 6

How is H. pylori infection diagnosed?

Answer 6

Endoscopy with biopsy
Urease breath test
Stool serology
Gram stain

Question 7

What is the treatment for H. pylori infection?

Answer 7

PPI/H2 + 2 antibiotics

Omeprazole + Metronidazole + Clarithromycin

Question 8

What is the most common cause of GI infection in the developed world?

Answer 8

Campylobacter Jejuni

Question 9

Patient has enteric infection with ascending weakness/paralysis?

Answer 9

Guillain-Barre syndrome secondary to campylobacter Jejuni infection.

Question 10

What are the microbiological characteristics of Campylobacter jejuni?

Answer 10

Thin curved gram- rods
Gullwinged
Microaerophilic

Sheep, Cattle, birds, and dogs are reservoirs

Question 11

What is the common presentation of infection with Campylobacter jejuni?

Answer 11

Fever
appendicitis like abd pain
Watery diarrhea –> dysentery with blood/pus

Following 1 week incubation.

Question 12

How is C. jejuni diagnosed?

Answer 12

Culture on media that prevent normal bacterial growth

Question 13

How is C. jejuni treated?

Answer 13

Erythromycin

Alternatively, may use FQs but resistance in common

Question 14

What are the microbiological characteristics of V. cholerae?

Answer 14

Motile (polar flagella), Gram-, ox+ curved bacilli

Found in aquatic ecosystems and grow in high pH

Question 15

What are the virulence factors for V. cholerae?

Answer 15

Cholera toxin (phage encoded)
Toxin co-regulated pilus (TCP)

Question 16

With what conditions are V cholera infections associated?

Answer 16

poor sanitation/sewage
More common in warm months
infection by brackish water, shellfish

Question 17

What is the pathogenesis of V. cholera?

Answer 17

Attach to small intestine via TCP –> cholera toxin (ADP-ribosylates GTP bp) –> increased Adenylate cyclase activity –> increase cAMP –> Increased CFTR activity –> Increased secretion of Cl- and H2O –> secretory diarrhea

Question 18

What is the presentation of V. cholera infection?

Answer 18

Abrupt, severe, diarrhea, vomiting and rice water stools up to 20L per day. Can lead to death from dehydration

Question 19

How is V. cholera diagnosed?

Answer 19

TCBS + McConkey agar

Question 20

What is the treatment for V. cholera infection?

Answer 20

IV fluids and electrolytes with oral glucose

Doxy, erythromycin

Question 21

What is the most common food borne illness in Japan?

Answer 21

Vibrio parahemolyticus

Associated with raw shellfish and sea water