Comparative evaluation of selective media and key factors affecting isolation of V. cholerae and V. parahaemolyticus

Abstract

Abstract Thiosulfate citrate bile salts sucrose (TCBS) agar is a widely used selective medium for the presumptive isolation of Vibrio spp, playing an essential role in food safety and public health surveillance. However, variations among commercial formulations may significantly affect detection accuracy. In this study, seven commercial TCBS agar formulations were systematically evaluated for their ability to support the growth and colony development of Vibrio cholerae and Vibrio parahaemolyticus strains, and inhibition of non-target bacteria. The effects of pH, as well as the source and concentration of bovine bile salts, on medium performance were also investigated. The results revealed significant differences among formulations in the recovery of the tested V. cholerae and V. parahaemolyticus strains and in selectivity against non-target bacteria. Media with stronger inhibition of competing bacteria generally exhibited reduced recovery of target Vibrio , indicating a trade-off between sensitivity and specificity. Both the source and concentration of bile salts influenced medium performance. Alkaline conditions (pH 8.4–9.2) supported recovery of the two target Vibrio species while improving inhibition of non-target bacteria. Collectively, this study provides experimental data on performance variability among commercial TCBS agar formulations and offers useful insights for improving the reliability of presumptive isolation of the two target species and informing TCBS agar optimization. Key points Bile salt source and concentration contributed to variation in TCBS agar performance An alkaline pH range (8.4–9.2) promotes the growth of the two target Vibrio species while enhancing the selectivity of TCBS agar A trade-off exists between target-strain recovery and inhibition of non-target bacteria The findings provide practical insights for optimizing TCBS agar for the tested target strains