Rapid detection of Vibrio cholerae with a new selective enrichment medium and polymerase chain reaction

The inhibitory effect of metallic EDTA compounds on growth of Vibrio cholerae and Escherichia coli was studied. Only Fe-EDTA among the compounds tested showed pH-dependent growth inhibition on E. coli at pH 9.0, but no inhibition of V. cholerae at the same pH. By addition of Fe-EDTA as a selective inhibitor, a novel enrichment broth (tentatively designated as VCF broth) for the selective isolation and cultivation of V. cholerae from other Gram-negative bacilli has been developed, and the selective enrichment capacity of VCF broth for V. cholerae and selective inhibiting activity against E. coli were significantly higher than those of alkaline peptone water. A simple procedure for rapid detection of V. cholerae by selective enrichment for 6 hr with VCF broth and then amplification of the cholera toxin target DNA fragment by the polymerase chain reaction was presented. VCF broth may be a useful tool for the selective enrichment of V. cholerae in bacterial examinations.