Vibrio Gram negative curved comma shaped bacilli Aerobes
Vibrio Gram negative curved “comma shaped” bacilli. Aerobes and facultative anaerobes. Motile: possess “single polar” flagellum. Acid sensitive. Grow in alkaline condition. Halophiles. Oxidase positive.
Vibrio cholerae Classified into: Two biotypes: El Tor and Classical Biotypes. ‘O’ antigen Serotypes: O 1 and Non O 1 (e. g O 139 Capsulated (Bengal strain). O 1 contains 3 subtypes: Inaba. Ogawa. Hikojima.
Cholera Life threatening diarrheal illness. related to contamination of common water sources (water-born). occurs as “epidemic” and “pandemic”. Most pandemic were caused by O 1 serotypes (7 pandemic). One pandemic was caused by O 139 serotype in India and Bangladesh 1992. “Endemic” in India and Africa.
Cholera: diagnosis Specimen: stool. Transport media: Cary-Blair medium and Alkaline peptone water. Gram staining: gram negative comma shaped bacilli.
Cholera: diagnosis Culture: Selective media: Thiosulphate Citrate Bile Sucrose agar (TCBS): ferments sugar and produces yellow colonies. Motility test; positive. Biochemical reactions: Oxidase positive. Serotyping. Biotyping
Thiosulfate Citrate Bile Sucrose Agar Selective medium for vibrio cholerae. The high concentrations of thiosulfate and citrate and the strong alkalinity of this medium largely inhibit the growth of Enterobacteriaceae. Ox bile and cholate suppress primarily enterococci. Any coliform bacteria, which may grow, cannot metabolize sucrose. The mixed indicator thymol bluebromothymol blue changes its colour to yellow, when acid is formed, even in this strongly alkaline medium. TCBS agar 7
Alkaline peptone water Alkaline Peptone Water is an enrichment medium used forthe cultivation of Vibrio species from feces and other infected materials.
Vibrio cholerae • Oxidase test: The cytochrome oxidase enzyme catalyzes the transport of electrons from a donor compound to the final electron acceptor, oxygen. In this test, an artificial electron donor, phenylenediamine, a redox dye in its reduced form, is used to reduce the cytochrome oxidase. If the enzyme is present, the colorless dye will turn a purple to blue color. No color change is a negative test. Oxidase +ve.
Vibrio cholerae Motile.
Vibrio cholerae Biotyping: Classical biotype 1. Production of hemagglutinin 2. Sensitivity to bacteriophages 3. Sensitivity to Polymyxin 4. Voges-Proskauer test 5. Production of haemlysin El Tor biotype No Yes No Negative Positive No yes
Vibrio cholerae biotyping VP test Polymyxin sensitivity Eltor -Ve +Ve -Ve Cassical Bacteriophage IV sensitivity Eltor -Ve +Ve Eltor Hemolysin production Cassical -Ve +Ve Eltor
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