VALUE OF CELLOBIOSE-POLYMYXIN B-COLISTIN AGAR FOR ISOLATION OF VIBRIO-VULNIFICUS FROM OYSTERS

Twenty-eight samples, comprising a total of 224 oysters, were examined for the presence of Vibrio vulnificus. Oyster homogenates were plated onto cellobiose-polymyxin B-colistin (CPC) agar or V. vulnificus enum eration (VVE) agar, with subsequent hybridization with a gene probe sp ecific for this pathogen. Of over 3,500 cellobiose-positive colonies i nitially tested from CPC agar, 28.7% could be identified as V. vulnifi cus on the basis of probe hybridization. Of the 19,000 colonies develo ping on VVE agar, only 2.8% were identified as this species. When in s ubsequent CPC agar studies colony morphology as well as color was cons idered, 81.6% of over 1,000 colonies probed proved to be V. vulnificus . We conclude that CPC agar is highly selective for this pathogen, and may be effectively employed in monitoring studies to determine levels of this bacterium in molluscan shellfish.