vibrio spp.: gram negative rods Flashcards
the vibrio spp. are oxidase __
positive
pseudomonads are also oxidase positive;
enterobacteriae are oxidase negative
vibrio cholerae: character
oxidase positive, glucose and sucrose fermenter, motile with a flagella
vibrio cholerae: culture
grows on tiosulphate-citrate-bile-sucrose agar (TCBS), grows as yellow colonies
vibrio cholerae: transmission
faecal-oral
vibrio cholerae: virulence factors
cholera toxin:
b subunit binds to the ganglioside receptors on the enterocytes, the a subunit crosses the membrane to activate adenylate cyclase
over production of cAMP inhibits active reabsorption of Na+ and water, and increases anion extrusion (chloride and bicarbonate ions), causing sodium and hence water outflow
MAJOR DEHYDRATION
vibrio cholerae: clinical presentations
profuse watery diarrhoea - rice water stools with a fishy odour, typically without abdominal pain or fever, results in severe dehydration
can cause death within a day
- note: vibrio cholerae is non-invasive
- *epidemic strains include serotypes O1 and O139
name the epidemic strains of vibrio cholerae
serotypes O1 and O139
vibrio parahaemolyticus: character
oxidase positive, non-sucrose fermenter that thrives in salt water environments
vibrio parahaemolyticus: culture
grows on TCBS agar as green colonies since they are non-sucrose fermenting
vibrio parahaemolyticus: transmission
contaminated seafood
vibrio parahaemolyticus: virulence factors
enterotoxin
*invasive, unlike v. cholerae that is non invasive
vibrio cholerae: diagnosis
culture
vibrio cholerae: treatment
oral rehydration therapy through replacement of electrolytes and fluid; severe cases may require iv infusion otherwise oral rehydration salts are feasible
antibiotics: tetracycline or ciprofloxacin can be used to reduce period of pathogen excretion and severity of diarrhoea
