Prevalence of Vibrio cholerae in rivers of Mpumalanga province, South Africa as revealed by polyphasic characterization
Cholera is a life-threatening diarrhoeal disease, which mainly affects inhabitants of developing countries due to poor socio-economic conditions and lack of access to potable water and sanitation. Toxigenic Vibrio cholerae are the aetiological agents of cholera. These bacteria are autochthonous to aquatic environments, hence water plays a central role both in the epidemiology and transmission of cholera. The aim of this study was to determine the prevalence of V. cholerae from 32 sites of major rivers in Mpumalanga province of South Africa using a polyphasic approach. Water samples (594) collected over for 4 months were cultured on thiosulphate-citrate-bile salt-sucrose agar, and oxidase positive (88) isolates were subjected to biochemical tests and duplex polymerase chain reaction targeting the outer membrane protein (ompW) and cholera toxin (ctxAB) genes. All ompW PCR positive V. cholerae isolates were subjected to rfbO1 PCR. Fifteen isolates from Crocodile, Komati and Gutshwa rivers were assigned to V. cholerae by both biochemical tests and PCR, of which no isolates were positive for ctxAB and rfbO1 genes. The polyphasic approach was effective at revealing non-O1 and non-toxigenic V. cholerae in some rivers. Such information is important for raising awareness regarding the presence of V. cholerae so that precautionary measures are taken on time.
Key words: Vibrio cholerae, ompW gene, ctx gene, rfbO 1, surveillance.