COMPARISON OF 5 PLATING MEDIA FOR ISOLATION OF SALMONELLA SPECIES FROM HUMAN STOOLS

A comparative study was carried out to evaluate the performances of di fferent culture media for the recovery of Salmonella spp. from 1,000 r outine samples of human stools, By direct plating we tested Salmonella -Shigella agar (SS), Hektoen enteric agar (HE) bismuth sulfite agar (B S), novobiocin-brilliant green-glycerol-lactose agar (NBGL) and SM-ID medium (SM), and after selenite enrichment, we tested all of the media except HE, C-s-esterase and oxidase tests were used for the screening of Salmonella spp. on SS and HE, The total number of Salmonella isola tes from direct culture was 74, with respective sensitivities and posi tive predictive values (PPVs) of 78.4 and 61%, 64.9 and 18.7%, 36.5 an d 34.2%, 55.4 and 20.7%, and 39.2 and 43.9% for NBGL, SS, HE, BS, and SMID, respectively. After enrichment, the total number of Salmonella i solates was 88, The respective sensitivities and PPVs obtained were 90 .9 and 62.5%, 92 and 17%, 90.9 and 32% and 93.2 and 71.3% for NBGL, SS , BS, and SM, respectively. According to our results, NBGL in direct p lating was the medium with the highest sensitivity with respect to the sensitivities of the other media, with significant statistical differ ences (P < 0.05), Likewise, the PPV for NBGL was also the highest (61% ), After enrichment in selenite broth, the sensitivities of the four m edia tested were similar, with the best PPV obtained with SM (71.3%); this was followed by NBGL (62.5%), When C-s-esterase was used on SS or HE, the PPVs improved from less than 40% to about 100%.