ICMSF Methods Studies. XVI. Comparison of Salt Polymyxin Broth with Glucose Salt Teepol Broth for Enumerating Vibrio parahaemolyticus in Naturally Contaminated Samples

Abstract

Two media, glucose salt teepol broth (GSTB) and salt polymyxin broth (SPB), were compared for their efficacy in enumerating Vibrio parahaemolyticus in naturally contaminated samples using the most probable number (MPN) procedure. Eleven laboratories in four countries participated, six of them using two analysts. One hundred ninety-six of 335 samples were found to contain V. parahaemolyticus. Neither enrichment medium was superior, and both media appeared necessary to prevent false-negative results. There was a high (52.5%) percentage of MPN patterns that were improbable with respect to Poisson distribution in those MPN tubes that yielded V. parahaemolyticus. Suspect colonies that developed on thiosulfate citrate bile salts sucrose (TCBS) plates streaked from GSTB were confirmed (1,438/1,929 = 75%) about as frequently as when streaked from SPB (2,155/3,038 = 71%).