Comparison of CHROMagar Salmonella medium and Hektoen enteric agar for isolation of salmonellae from stool samples

CHROMagar Salmonella (CAS), a new chromogenic medium, was retrospectively c ompared to Nektoen enteric agar (HEA) with 501 Salmonella stock isolates an d was then prospectively compared to HEA for the detection and presumptive identification of Salmonella spp, with 508 stool samples before and after e nrichment, All stock cultures (100%), including cultures of H2S-negative Is olates, yielded typical mauve colonies on GAS, while 497 (99%) isolates pro duced typical lactose-negative, black-centered colonies on HEA. Following o vernight incubation at 37 degrees C, a total of 20 Salmonella strains were isolated from the 508 clinical samples. Sensitivities for primary plating a nd after enrichment Here 95% (19 isolates) and 100% (20 isolates), respecti vely, for CAS and 80% (16 isolates) and 100% (20 isolates), respectively, f or HEA. The specificity of CAS (88.9%) was significantly higher than that o f HEA (78.5%; P < 0.0001), On the basis of its good sensitivity and specifi city, CAS medium can be recommended for use for primary plating when human stool samples are screened for Salmonella spp.