Evaluation of Selective Broth Media for Development of a Most Probable Number (MPN) Quantification Method for Vibrio cholerae

Cholera outbreaks may be mitigated by monitoring drinking waters for the bacterial disease agent, Vibrio cholerae. However, present microbial methods for V. cholerae require advanced training and specialized equipment, limiting their use in low-resource settings that are most vulnerable to cholera outbreaks. We hypothesized that we could simplify sample analysis through one-step liquid culture-based quantification of V. cholerae. In this study, we evaluated selective culture media for V. cholerae that could be adapted for culture and quantification of the organism in liquid samples using a most probable number (MPN) format. We evaluated previously described and newly derived selective V. cholerae broth culture media for exclusivity against non-target organisms and for productivity in culturing representative V. cholerae strains, including O1 El Tor Ogawa, O139, and non-O1. Among previously described media, CHROMagar Vibrio and taurocholate tellurite-based media demonstrated the best balance of exclusivity and productivity in broth format, although productivity varied by V. cholerae strain. Newly proposed formulations improved exclusivity in some cases, particularly with the addition of the antibiotics fosfomycin and streptomycin. Overall, these results demonstrate the promise of selective broth media for one-step liquid-based culture of Vibrio cholerae under laboratory conditions, but further optimization is necessary prior to implementation with complex water samples and field deployment.