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Practical No.19 Vibrio cholerae

Practical No.19 Vibrio cholerae. Is a  Gram negative  comma-shaped bacterium  with a polar  flagellum  that causes  cholera  in  humans . There are three main types of   V. cholerae according to their antigenic structure; a-classical type b- El tor c- ogawa d- inaba

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Practical No.19 Vibrio cholerae

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  1. Practical No.19 Vibrio cholerae

  2. Is a Gram negative comma-shaped bacterium with a polar flagellum that causes cholera in humans. • There are three main types of  V. cholerae according to their antigenic structure; • a-classical type • b- El tor • c- ogawa • d- inaba • V. cholerae enters the human body through ingestion of contaminated food or water. The bacterium enters the intestine, imbeds itself in the villi, replicates and releases cholera toxin.

  3. Vibrio • Short • Rigid • Gram -ve • Single flagellum • Comma (,) shape - called ‘Comma’ vibrio

  4. Laboratory diagnosis: • Specimen: • Stool, rarely vomit. • Transport media include; • sea salt medium , which is highly alkaline due to high Nacl • Alkaline peptone water. enrichment broth,

  5. Presentation- Rice water diarrheal Dr.T.V.Rao MD

  6. Culture: • 1- TCBS; (Thiosulfate citrate bile salt sucrose.) is a selective agar medium • Indicator – bromothymol blue ..Control is green ( prepared as plates ) • After inoculation with suspected bacteria and a 18 to 24 hours’ incubation at 35° to 37°C on TCBS agar ,Colonies suspicious for V. cholerae will appear as yellow, shiny colonies, 2 to 4 mm in diameter. The yellow color is caused by the fermentation of sucrose in the medium. Sucrose-nonfermenting organisms, such as V. parahaemolyticus, produce green to blue-green colonies.

  7. Flame & Cool Flame & Cool Flame & Cool Identification of Vibrio Differentiation between SF & NSF byGrowth on TCBS • Method: • TCBS agar is inoculated with tested organism recovered from alkaline peptone waterusing streak plate technique • Incubate the plate in incubator at 37 C/24 hrs • Results: • SF organism appears as yellow colonies (V. cholerae) • NSF organism appears as blue to green colonies (V. parahaemolyticus) 2 1 3 4 5

  8. 2- S.S agar • 3- Alkaline peptone water • 4- Sea salt medium. • Biochemical tests: • Vibrio cholerae appears as a non lactose fermenter • Motile • Urease -ve • Oxidase +ve . development of a dark purple color within 10 seconds. • TSI ; A/A Gas –ve, H2S –ve

  9. Toxins: Besides endotoxin, the following toxins and enzymes have been described: 1. Enterotoxin 2. Vascular permeability factor 3. Sodium pump inhibition 4. Cytotoxin 5. Hemolysin 6. Mucinase

  10. Thank You

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