Evaluation of a pectin agar medium for isolation of Yersinia enterocolitica within 48 hours.

A modified pectin agar medium was evaluated for the rapid isolation and presumptive identification of Yersinia enterocolitica. Of 118 isolates of Enterobacteriaceae tested, only the 13Y. enterocolitica and the three Klebsiella oxytoca strains produced colonies that depressed and sank into the agar. Yersinia enterocolitica was also easily identified in mixed cultures, even from inocula containing three times as many other Enterobacteriaceae organisms as Y. enterocolitica. The recovery of Y. enterocolitica was evaluated on Mueller-Hinton, pectin, Hektoen enteric, xylose lysine desoxycholate, Salmonella-Shigella, and MacConkey agars. Compared with Mueller-Hinton agar, the pectin agar showed a 100% recovery of Y. enterocolitica, with all strains having depressed colonies, while the other media showed lesser recoveries of only 5 to 25%, with no other discriminating colonial characteristic.