Evaluation of a new chromogenic medium, chromID Vibrio, for the isolation and presumptive identification of Vibrio cholerae and Vibrio parahaemolyticus from human clinical specimens.

The aim of this study was to evaluate the performance of the chromID Vibrio medium for the detection of Vibrio cholerae and V. parahaemolyticus in stool and swab specimens in comparison with thiosulfate citrate bile salts sucrose (TCBS) medium. A total of 96 samples including 30 fresh stool, 32 stool, and 34 swab specimens originating from routine laboratories were tested. All samples were seeded on both media, the TCBS medium and the chromID Vibrio, directly and after an enrichment step on alkaline peptone water. Of the 96 samples studied, 34 were positive for V. cholerae and 30 were positive for V. parahaemolyticus. The sensitivity for the isolation of V. cholerae in fresh stool specimens was identical for both media, 78.5% and 100% before and after enrichment, respectively. However, positive test with chromID Vibrio concluded immediately to the presence of V. cholerae. In the case of artificial contaminations, the sensitivity of chromID Vibrio was more important than TCBS after enrichment for V. cholerae and for V. parahaemolyticus before and after enrichment. In fresh stool specimens, the specificity of chromID Vibrio for screening V. cholerae was significantly higher than TCBS (100% and 100% compared to 50% and 50% before and after enrichment, respectively) and was important for V. parahaemolyticus (100% chromID Vibrio; 93.33% TCBS).