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Vibrio Cholerae laboratory diagnosis and confirmation

Presumptive diagnosis:

I)  Immobilization test: A rapid presumptive diagnosis of cholera can be made by observing the wet smear for the distinctive rapid to and fro movement (darting movement) of V. cholerae O1 and O139 due to their single polar flagellum. The movement can be stopped by adding one drop of V. cholerae O1 and O139 antiserum respectively.

Hanging drop method for Vibrio cholerae is one of the easy but most popular test used for the presumptive diagnosis. Read details about this test here

II)  Oxidase test: on performing oxidase test from a pure culture on Macconkey agar or nutrient agar, positive reaction is observed. (Note: However, Aeromonas spp also gives a positive oxidase test result so further confirmation is necessary by culture and serotyping)

1. Cultural characteristics:

Biotyping:

                                 Test

Classical

E1 Tor

(1)

Chicken cell Agglutination (2.5% RBC)

__

+

(2)

Polymyxin B sensitivity (50 IU/disc)

S

R

Key: S = Sensitive, R = Resistant, + = Positive, – =  Negative