Effect of storage conditions of the performance of bismuth sulfite agar

Refrigerated storage of bismuth sulfite agar plates for up to 4 days did not adversely affect growth and colonial characteristics of selected Salmonella strains. Incubation of inoculated plates for 48 h favored the development of more salmonellae with typical morphology. Inoculated plates of freshly poured medium incubated for 48 h gave recoveries similar to those on refrigerated plates and showed a high selectivity against Citrobacter freundii and Proteus vulgaris, organisms which mimic the colonial characteristics of Salmonella on this medium. The use of bismuth sulfite plates stored at room temperature for more than 2 days should be avoided.