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:O1 and Non O1 (e.g O139 Capsulated (Bengal strain).

O1 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 O1 serotypes (7 pandemic).

One pandemic was caused by O139 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 blue-bromothymol blue changes its colour to yellow, when acid is formed, even in this strongly alkaline medium.

7

TCBS agar

Alkaline peptone water

Alkaline Peptone Water is an enrichment medium used forthe cultivation of Vibrio species from feces and other infected materials.

Oxidase +ve.

• 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.

Vibrio cholerae

Motile.

Vibrio cholerae

Biotyping:

Classical biotype El Tor biotype

1.Production of hemagglutinin  No Yes

2.Sensitivity to bacteriophages Yes No

3.Sensitivity to Polymyxin Yes No 4.Voges-Proskauer test Negative Positive 5.Production of haemlysin No yes

Vibrio cholerae

Vibrio cholerae biotyping

Eltor

Eltor

Cassical

Cassical

Eltor

Eltor-Ve

Polymyxin sensitivity VP test

Bacteriophage IV sensitivity Hemolysin production

+Ve

+Ve +Ve

+Ve-Ve

-Ve -Ve