ISOLATION OF VERO CYTOTOXIN-PRODUCING ESCHERICHIA-COLI O157 FROM WILDBIRDS

In a survey of wild birds (mainly gulls), 0.9% of the bacterial isolat es from faecal samples at an urban landfill site and 2.9% of bacterial isolates from faecal samples on intertidal sediments in Morecambe Bay were Vero cytotoxin-producing Escherichia roll O157. Isolation proced ures employing commonly used cultural methods were hindered by the sel ection of A large number of false positives. The only procedure which resulted in the isolation of E. roll O157 from bird faecal samples was : enrichment (18 h) in a selective tryptone soya broth followed by fil tration using hydrophobic grid membranes and growth on Chromagar(R) O1 57. The majority of isolates selected as potential E. coli O157 by cha racteristic growth on Chromagar(R) O157 could be eliminated by subsequ ent growth on CT-SMAC or CR-SMAC This second identification (character ization) stage reduced the number of potential E. roll O157 requiring further confirmation by typing methods (serotype and Vero cytotoxin) b y more than 70%.