Microbiology: Enteric Bugs-Bacteria Flashcards
What are the microbiological characteristics of H. pylori?
Slender curved Gram negative rod
Microaerophilic
Similar to campylobacter
What are the virulence factors of H. pylori?
- Urease (buffers H+)
- Vacuolating cytotoxin (from PAI)
- Cytotoxin associated Protein (CagA)
- Pilli
In what populations is H. pylori infection most common?
Elderly and those of low socioeconomic status.
What is the Pathogenesis of H. pylori infection?
fecal-oral transmission –> bacteria grow in stomach via urease –> Immune system cannot remove H. pylori b/c non-invasive –> Immune mediated damage.
What diseases are caused by H. pylori?
Duodenal ulcers (90%) Gastric ulcers (70%) Gastric adenocarcinoma/lymphoma
How is H. pylori infection diagnosed?
Endoscopy with biopsy
Urease breath test
Stool serology
Gram stain
What is the treatment for H. pylori infection?
PPI/H2 + 2 antibiotics
Omeprazole + Metronidazole + Clarithromycin
What is the most common cause of GI infection in the developed world?
Campylobacter Jejuni
Patient has enteric infection with ascending weakness/paralysis?
Guillain-Barre syndrome secondary to campylobacter Jejuni infection.
What are the microbiological characteristics of Campylobacter jejuni?
Thin curved gram- rods
Gullwinged
Microaerophilic
Sheep, Cattle, birds, and dogs are reservoirs
What is the common presentation of infection with Campylobacter jejuni?
Fever
appendicitis like abd pain
Watery diarrhea –> dysentery with blood/pus
Following 1 week incubation.
How is C. jejuni diagnosed?
Culture on media that prevent normal bacterial growth
How is C. jejuni treated?
Erythromycin
Alternatively, may use FQs but resistance in common
What are the microbiological characteristics of V. cholerae?
Motile (polar flagella), Gram-, ox+ curved bacilli
Found in aquatic ecosystems and grow in high pH
What are the virulence factors for V. cholerae?
Cholera toxin (phage encoded) Toxin co-regulated pilus (TCP)
With what conditions are V cholera infections associated?
poor sanitation/sewage
More common in warm months
infection by brackish water, shellfish
What is the pathogenesis of V. cholera?
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
What is the presentation of V. cholera infection?
Abrupt, severe, diarrhea, vomiting and rice water stools up to 20L per day. Can lead to death from dehydration
How is V. cholera diagnosed?
TCBS + McConkey agar
What is the treatment for V. cholera infection?
IV fluids and electrolytes with oral glucose
Doxy, erythromycin
What is the most common food borne illness in Japan?
Vibrio parahemolyticus
Associated with raw shellfish and sea water
