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Flashcards in Bacteria in Gut Deck (14)
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What are the two types of enteric pathogens?

ones that always cause disease (shigella)
harmless as long as they remain in GI tract (klebsiella) = opportunistic


What three bacterial structures are involved in serotyping enteric bacteria?

O antigen - LPS of outer membrane = endotoxin
H antigen = flagellum
K antigen - capsule


What are the three components of LPS?

lipid A - responsible for toxic properties
core polysaccharide and O antigen polysaccharide side chain


What do the A and B components of the heat labile toxin of ETEC do?

B - binds to ganglioside and glycoprotein receptors on brush border
A - causes fluid secretion by activating adenylyl cyclase in NAD-dependent manner


What does the ST toxin of ETEC do?

binds to transmembrane guanylate cyclase receptor protein and causes intestinal secretion by increased cGMP


What diseases can E. coli cause outside the GI tract?

bacteremia and respiratory tract inf
K1 strains - neonatal meningitis


What are other opportunistic pathogens in addition to E. coli?

klebsiella - alcoholics, polysaccharide capsule
enterobacter - contaminated IV lines
serratia - pink-red colonies, indwelling catheters
proteus - UTI, struvite kidney stones


What is the microbiology of salmonella?

don't ferment lactose
motile w flagella
s. typhi has capsule = Vi antigen --> vaccine


What is the microbiology of shigella?

four species, three don't ferment lactose
no flagella
dysenteriae type 1 - shiga toxin


What is the microbiology of vibrio cholerae?

O1 and O139 cause epidemic cholera in ppl
oxidase positive, isolated by TCBS agar
single polar flagellum


How does vibrio cholerae survive in brackish waters?

converts from growing cell into dormant one which cannot be grown on laboratory media


What are the non-epidemic vibrio cholerae strains characteristics?

not O1 or O139, no cholera toxin
cause gastroenteritis, septicemia in debilitated persons


What are the non-cholera vibrios?

parahemolyticus - U.S coastline (fish), wound inf, no antimicrobials unless severe
vulnificus - sea water, inf wounds, more virulent --> serious wound inf in chronic dz (1 in 2 die) - ANTIBIOTICS!


What is the microbiology of campylobacter?

zoonosis, jejuni and coli cause gastroenteritis, obligate microaerophiles