Microbiology - Vibrio, Campylobacter, Helicobacter - Rebecca Greenblatt Flashcards
Phlyogeny: vibrio cholera
gram negative rod;
oxidase positive
facultative anaerobe
What strains of vibrio cholera cause epidemic disease?
O1 and O139 - O cell wall antigen indicates pathogenicity
Transmission: Vibrio cholera
Fecal-oral;
Usually killed by stomach acid;
High IU
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?
Enterotoxin
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 agarPhylogeny: V. Parahaemolyticus
Gram neg
Oxidase pos
Curved and motile
Halophile
more common than V. vulnificus
How does V. parahaemolyticus usually present?
Mild gastroenteritis
found in shellfish
Phylogeny: Vibrio vulnificus
Gram neg Oxidase pos Curved and motile some are encapsulated Halophile 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?
Protease exotoxin;
Hemolysin
Phylogeny: Campylobacter
Gram neg Comma or S shaped Ox pos Cat pos *microaerophilic*
Transmission: Campylobacter
fecal-oral (raw milk, undercooked chicken), sexual contact, sick pets (puppies)
