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Vibrio cholerae.

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Presentation on theme: "Vibrio cholerae."— Presentation transcript:

1 Vibrio cholerae

2 Cholera





7 Vibrio sp. Gram-negative rods Curves or comma shaped Non-spore forming
Highly motile-single polar flagella Associated with salt water Oxidase positive Facultative anaerobe Tolerate alkaline conditions to pH9.0 Readily cultivated, Simple nutritional requirements


9 Vibrio Vibrio cholerae -gastroenteritis
Vibrio parahaemolyticus -gastroenteritis, wound infection, bacteremia Vibrio vulnificus -wound infection, bacteremia

10 Vibrio cholerae Antigenic structure
Common heat-labile flagellar H antigen O lipopolysaccharide confers serologic specificity More than 150 O antigen serogroups Only O-1 and 0139 serogroups cause Asiatic cholera Three serotypes; Ogawa, Inaba, Hikojima Two biovars; classic and El Tor

11 2 biotypes of serogroup O-1
Classical biotype El Tor biotype. Serogroup 139

12 V. cholerae - Transmission
feces water fresh salt food

13 Vibrio cholerae Epidemiology
Epidemic cholera-spread by contaminated water under conditions of poor sanitation Endemic-consumption of raw seafood Copepods


15 Vibrio cholerae Pathogenesis Ingest 108-1010 organisms
Non invasive infection of small intestine Organisms secrete enterotoxin Watery diarrhea


17 Virulence factors of V.cholerae O1 and O139
Biological effect Cholera toxin Hypersecretic of electrolytes and water Coregulated pilus Adherence to mucosal cells adhesin Accessory colonization factor adhesin Hemagglutination protease Releases bacteria from mucosal cells Zona occludens Exotoxin Accessory cholera enterotoxin Flagellum Motility Siderophores Iron sequestration

18 Cholera toxin Enterotoxin-cholera toxin-CtxAB Encoded by a prophage
Molecular mass of 84,000 daltons A subunit-ADP-ribosylating toxin B subunit-bind GM1-gangliosides on enterocytes A subunit ADP ribosylates Gs-alpha which regulates activation of adenlyate cyclase Result is persistent increase in cAMP levels Hyper secretion of Na, Cl, K, bicarbonate and H20



21 Vibrio cholerae-Clinical manifestations
Asymptomatic colonization to fatal diarrhea Onset 2-3 days after ingestion Abrupt onset of watery diarrhea and vomiting Rice water stools Severe fluid and electrolyte loss-dehydration, metabolic acidosis, hypovolemic shock, renal failure Death 60% if untreated, 1% if treated for fluid loss

22 Pathogenicity of V. cholera
Dehydration and death Massive secretion of ions/water into gut lumen

23 Immunity Strong immunity after recovery, SIgA

24 Bacteriological Diagnosis
Specimens: stool, vomitus. Stained smear Culture: alkaline peptone water of agar plate, and TCBS agar plate. Quick immunological methods: immunofluorescent “ball” test; PCR.

25 Vibrio-Prevention and Control
Improved sanitation Fluid and electrolyte replacement Antibiotic prophylaxis Improved food handling

26 Vibrio parahemolyticus
One kind of halophilic vibrios; optimal NaCl concentration contained in culture media is 3.5%; hemolysin related to its pathogenicity, can be detected by human or rabbit RBC test (Kanagawa test); cause food poisoning in human beings. raw sea-food

27 Vibrio parahaemolyticus
Clinical manifestations Self-limiting diarrhea to mild cholera-like illness 24 hours after ingestion-explosive water diarrhea Headache, abdominal cramps, nausea, vomiting, low grade fever for 72 hours or more Uneventful recovery Wound infections in people exposed to seawater-containing vibrios

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