XLT Agar (Xylose Lysine Tergitol-4) Is a selective culture medium for the isolation and identification of salmonellae from food and environmental samples. It is similar to XLD agar however the agar is supplemented with the surfactant, Tergitol 4, which causes inhibition of Proteus spp. and other non-Salmonellae. Successful growth of Salmonella will result in growth of red colonies with a black centre.
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XLT agar Wikipedia(Text) CC BY-SA