A SIMPLIFIED DIAGNOSTIC ASSAY FOR THE IDE NTIFICATION OF CYTOTOXIC NECROTIZING FACTOR-PRODUCING ESCHERICHIA-COLI (CNF) ISOLATED MAINLY FROMBOVINES

Six hundred E.coli strains isolated mainly from bovines were analysed for fermentation of L-sorbose and production of an a-hemolysine. The 6 00 strains could be subdivided based on production of the CNF toxin: 1 00 strains produced the CNF1 toxin, 94 the CNF2 toxin while 406 remain ed negative for both toxins. The CNF1 strains were positive for both p arameters in 87 % of the cases, CNF2 strains were positive in 46 % aga inst only 22 % of the CNF-negative strains. We conclude that the ferme ntation of sorbose and the production of an a-hemolysine are two chara cteristics that can easily be analysed' and that can guide the diagnos tic of CNF strains, especially the diagnosis of CNF1 strains.