DETERMINATION OF THE EFFECTIVENESS OF NOVOBIOCIN ADDED TO TWO AGAR PLATING MEDIA FOR THE ISOLATION OF SALMONELLA FROM FRESH MEAT PRODUCTS

Abstract

Five plating media, Hektoen enteric (HE) and xylose lysine deoxycholate (XLD) agars with and without 80 and 5 μg/ml of novobiocin (N), respectively, and brilliant greeen sulfadiazine (BGS) agar with 80 μg/ml of the antimicrobial agent, were analyzed for the recovery of salmonellae from various fresh beef, pork, and poultry meat products. Of the total Samonella positive samples, 50.0% and 82.5% were found on XLD and XLD‐N agars, respectively, 75.0% and 85.0% on HE and HE‐N agars, respectively and 65.0% on BGS agar. HE‐N and BGS media isolated three times more false positives than did XLD‐N agar, while XLD and HE agars gave the highest numbers of false positives. The major H2S producing false positive on XLD and HE agars was Proteus mirabilis. With the addition of N, P. mirabilis was eliminated, and the major H2S producing false positive was almost exclusively Citrobacter freundii. The false positives on BGS agar were predominately distributed among C. freundii, Enterobacter sp., and Klebsiella sp.