Wednesday, October 03, 2007

Isolation and Identification of Salmonella spp. from Clinical/Food Sample

               The red colonies with black centers and media turn red (phenol red as indicator) in Xylose lysine deoxycholate (XLD) agar media distinguish Salmonella spp. from other coliforms that help to separate from other bacteria present in clinical blood/stool and food sample. Also, this method and media can be used to check contamination after antibacterial assay of Salmonella spp.
               Salmonellae can metabolize thiosulfate and produce hydrogen sulfide, hence black centers seen in colony but Shigellae can't and remains pink colony. Other coliforms are seen as yellow/orange colonies.
                Thus I separated Salmonella spp. very quickly from rest of the organisms.

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