CHROMOGENIC VIBRIO AGAR *

Description

Vibrios have played a significant role in human history. Outbreaks of cholera, caused by Vibrio cholerae, can be traced back in time to early recorded descriptions of enteric infections. The Vibrios have also received the attention of marine microbiologists who observed that the readily cultured bacterial population in near-shore waters and those associated with fish and shell fish were predominantly Vibrio species. Vibrio species are mainly responsible for causing cholera and food poisoning in humans. Vibrio cholerae causes cholera due to the intake of contaminated food such as raw oysters. Vibrio parahaemolyticus is a major cause of food borne infections, causing food poisoning. Since Vibrio species naturally occur in sea water, worth special mention is their need for sodium chloride, although some species can grow with minimum sodium chloride concentration. The widely used media for Vibrio isolation are TCBS Agar and Alkaline Peptone Water. However accompanying sucrose-fermenting bacteria pose a problem in the identification of Vibrio species on TCBS Agar. On Chromogenic Vibrio Agar, the colour development by Vibrio species in not affected by the presence of colonies of other bacteria. This is because, the amount of colour developed depends on the reaction of the bacterial beta-galactosidase with the substrate contained in the media