Flashcards in Microbiology - Vibrio, Campylobacter, Helicobacter - Rebecca Greenblatt Deck (30):
Phlyogeny: vibrio cholera
gram negative rod;
What strains of vibrio cholera cause epidemic disease?
O1 and O139 - O cell wall antigen indicates pathogenicity
Transmission: Vibrio cholera
Usually killed by stomach acid;
Virulence factor: Vibrio cholera
Mucinase to clear brush border, attach with toxin-coregulated pilus;
Growing bacteria secrete cholera toxin
What kind of toxin is cholera toxin?
AB subunit structure
B binds ganglioside receptor GM1 on intestinal lining
Toxin carried by lysogenic bacteriophage CTX
Persistent activation of adenylate cyclase leads to what in the pathogenesis of vibrio cholera?
Loss of water and ions;
no absorption by microvilli, only secretion from crypts;
Massive watery diarrhea
What are the complications of v. cholera?
Acidosis and hypokalemia from severe dehydration
loss of bicarbonate and K
Culture V. cholera on:
Salt agar ("halophile");
Buffered media (ox pos, ferments sucrose);
acid-rxn on triple sugar iron agar
Phylogeny: V. Parahaemolyticus
Curved and motile
more common than V. vulnificus
How does V. parahaemolyticus usually present?
found in shellfish
Phylogeny: Vibrio vulnificus
Curved and motile
some are encapsulated
Produces siderophores - infection exacerbated by iron overload
Warm ocean water
Wounds contaminated by shellfish or ocean water causes:
Severe cellulitis if contaminated by V. Vulnificus
Septicemia with hemorrhagic bullae
What toxins are used by V. Vulnificus?
Comma or S shaped
fecal-oral (raw milk, undercooked chicken), sexual contact, sick pets (puppies)
guts of domestic animals: ~100% poultry asymptomatically infected
What is the IU for Campylobacter?
About 500 IU (very low)
Bloody diarrhea with pus, crypt ulcerations (can have watery diarrhea also)
About 3-5 days
Self-limited but complications possible
What kind of Campylobacter is strongly predisposing for Guillan-Barre syndrome?
Serotype O:19 antigenic cross-reactivity with neural glycosphingolipids
What are two less common complications of C. jejuni?
Does Campylobacter use M cells to cross the intestinal wall?
No; attaches directly
How do you culture Campylobacter?
Stool sample culture at high and low temp (growth fails at low temp)
"Seagull" appearance on microscopy is associated with what bug?
Treat the immunocomprimised adult with Campylobacter infection with:
Treat children with Campylobacter infection with:
Phylogeny: H. Pylori
Gram negative rods
Strongly Urease pos
How can you tell a vibrio infection from a heliobacter infection?
Heliobacter can survive stomach acid
Virulence: H. pylori
Bacteria attach to mucus-secreting cells of stomach w/ flagella virulence factor;
Break down urea into ammonia w/ urease;
Ammonia **neutralizes stomach pH**, allowing bacterial growth and irritating stomach lining
What infiltrate is caused by H. pylori?
infiltrate by neutrophils, T and B lymphocytes, macrophages and mast cells