- polysaccharide capsule - local epidemic in Calcutta

Vibrios Flashcards by Ayden Zarkhah

Gram negative or positive

Gram negative

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Physical shape of bacteria

Comma shaped rod

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Flagellum and nucleic acid

polar flagellum

- 2 circular chromosomes

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pH sensitivity of vibrio

highly alkali tolerant(pH 9)

- acid sensitive(pH<6)

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Relationship between vibrios and copepods

halotolerant and some halophilic(saline environments)

- resident on copepods

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Major type of V. cholerae

O1 strain with no capsule

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2 types of biotypes of O1 strain

Classical and El Tor

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2 serotypes of each biotype

Ogawa and Inaba

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Mutation type of El Tor

Mutation into O139

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Description of O139

polysaccharide capsule

- local epidemic in Calcutta

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Difference between El Tor and Classical

polymyxin resistant
produces hemolysin
less toxic produced, but colonized better
outgrows classical biotype in mixed culture

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Pandemics due to Classical and El Tor

Classical biotype for 6 pandemics

- El Tor biotype for 1961-2001 pandemics

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Colony numbers required for bacteria

large numbers of bacteria to colonize(10^6)

- with antacid, 10^3 and El Tor advantage

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Location where disease presents

Mainly small intestines

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Incubation period and initial presentation

1 to 4 days

- Nausea, vomiting, 1-2 loose stools

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Acute onset of clinical presentation

watery diarrhea(>20L per day), like rice water stool
contains mucus, lots of vibrio, no blood
no fever or pain

Risk of watery diarrhea due to V. Cholerae

-dehydration and electrolytes loss causes circulatory collapse and death

Epidemiological of V. Cholerae

worldwide distribution in water

- filtration of copepods, and sari cloth

Natural host of V. Cholerae

-humans

Spread of V. Cholerae

-ingested in fecally contaminated water or food

Onset of V. Cholerae

usually a few days
may carry bacteria for 3-4wks
rare long term carriers

Pathogenesis of V. Cholerae

-fimbriae bind to gut epithelium

Toxin of V. Cholerae

toxin and pilus genes regulated by ToxT

- ToxT mRNA is regulated by temperature-sensitive riboswitch

Toxin description

AB5 toxin, A is in 2 subunits linked by S-S
B binds as pentamer to receptor ganglioside Gm1(epithelial)
A1/A2 S-S bond is reduced and A1 uses NAD to ADP ribosylate a Gs protein

Consequence of S-S bond being reduced

- activates adenyl cyclase - increase cAMP causes ion secretion into gut lumen - water follows to balance osmolarity

Control of V. Cholerae

- rehydration and electrolyte replacement - Oral Rehydration salts - doycycline can limit vibrios shedding(only >10%) - vaccines not very effective

Clinical of V. Parahemolyticus

- halophilic - 12 to 24hrs incubation, nausea, vomiting, watery to bloody diarrhea, possibility gastroenteritis - self limiting, resolves 1-4 days

Epidemiological of V. Parahemolyticus

- worldwide distribution in ocean waters - consumed in contaminated(raw or undercooked seafood) - Japan and Atlantic coast

Pathogenesis of V. Parahemolyticus

-biofilms, T3SS, T6SS, hemolytic/cytotoxic enterotoxin

Control of V. Parahemolyticus

- rehydration and electrolyte replacement | - doxycycline if necessary

Clinical of V. Vulnificus

- infected wounds from handling contaminated seafood - bacteremia from eating raw oysters - very rapid cellulitis and necrosis - eventual liver damage(alcoholic predisposition)

Epidemiology of V. Vulnificus

- always associated with contaminated seawater or seafood | - endemic in TX, AL, LA

Pathogenesis of V. Vulnificus

- antiphagocytic capsule contributes to virulence | - necrotizing cytotoxin

Control of V. Vulnificus

- doxycycline right away - Cipro. if pregnant - takes 18hrs to get a positive culture; too late