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16 Cards in this Set

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  • Back
what are the general biologic components of vibrio?
gram neg rods, associated with salt water, single polar flagella, non spore forming, oxidase positive(distinguishes it from other diarrhea causers), facultative anaerobe, and two chromosomes (the smaller non ancestral one contains an integron that is good at capturing antibiotic resistant genes)
what are the antigenic agents of vibrio cholerae?
heat labile (therefore must be aprotein) flagellar H antigen, LPS with specefic serology, 200 O antigens (O1 and O130 can cause asiatic cholera), 3 serotypes of Ogawa, Inaba, and hikojima; two biotypes: classic and El Tor (El tor is less virulent and colonizes more). Also it forms biofilms. enterotoxin
describe the epidemiology of V cholerae
epidemics are caused by contaminated water under conditions of poor sanitation, endemic-consumption of raw seafood, all caused by copepods that are infected. Note common in India during monsoon season
how many orgs need to be ingested for pathogenesis?
10^8+ bc they are sensitive to acid.
where does vibrio cholerae infect and what does it do?
it is a noninvasive pathogen of the small intestine and it can cause death with its watery diarrhea
where and how do vibrio cholera form micro-colonies?
in the small intestine microvilli via pili. This pilus is called toxin coregulated pillus, is encoded by a prophage, and mutants of it are avirulent
describe the structure, function, and origination of the cholera toxin.
it is an enterotoxin with AB subunits, A subunit is ADP ribosylating, B subunitu binds gangliosides or enterocytes. A subunit ADP ribosylates Gs alpha which turns on adenylate cyclase, increasing cAMP and thus hypersecretion of NA, Cl, K, bicarb, and H2O. toxin is encoded in a prophage that is in an operon
what are the characteristics of the gene that causes all the pathogenicity of v cholera?
the ToxR regulon is found on the small chrom in the org, carries both the cholera toxin and the toxin coredulated pillus, also has an accesspry colonization factor, two pathogenicity islands, and controls the production of these chemicals by monitoring the environment of the vibrios
what are the clinical manifestations of vibrio cholera?
can be from asymptomatic colonization to fatal diarrhea, onset 2 + days after ingestion, watery diarrhea and vomitting, rice water stools bc your loosing epi cells, severe fluid and electrolyte loss dehydration, metabolic acidosis, hypovolemic shock, renal failure, death in 60% if untreated
describe the clinical manifestations of vibrio parahaemolyticus.
self limiting diarrhea to mild cholera like, diarrhea, vomits, headach, low fever, uneventful recovery, can get wound infection in ppl exposed to seawater containing vibrios
what are the clinical manifestations of vibrio vulnificus?
rapidly progressive wound infection following exposure to seawater or consumption of raw oysters; mortality in patients with septicemis is 50% unless antimicrobial therapy is started soon. infection is worse in ppl with hepatic disease or immunosuppression
describe the lab techniques used while dealing with vibrio.
TCBS is used to grow v cholera and is selective for it and you will see yellow for cholera, the other vibrios will grow on it however. V parahaemolyticus and vulnificus both need extra salt in the media. all are oxidase positive, and you can serotype them but this is rarely performed
what are treatment options for vibrio species?
for cholera can only do fluid and electrolyte replacement bc the toxin is causing the disease and antibiotic will not kill the toxin. Can give oral rehydration salts that contain glucose, sodium, Cl, K, and thus the large intestine absorbs enough for person to remain alive. V. vulnificans wound or septic infection needs tetracycline quickly.
what are ways to prevent and control vibrio infection?
improved sanitation, antibiotic prophylaxis if you are going to India, improved food handling, hope of a new live-attenuated vaccine
describe the aeromonas bacs.
gram -, facultative, ubiquitous in fresh and brackish H20, gastroenteritis: acute in kids and chronic shigella like in adults, wound infection +/- bacteremia, opportunistic systemic disease in immunocompromised patients
describe the bac plesiomonas shigelloides
gram -, facultative, oxidase positive, multiple polar flagella, fresh water/estuarine waters, aquired via contact with water, consumption of seafood, exposure to reptile or amphibians, self limited gastroenteritis that is occasionally extra intestinal