Presence of Shiga toxin-producing Escherichia coli O157:H7 in living layer hens

To evaluate the presence of Shiga toxin-producing strains of Escherichia coli (STEC) of the O157:H7 serotype in living layer hens so as to analyse the role of this avian species as potential reservoir. Cloacal swabs were collected between November 2004 and November 2005 from four intensive management layer hen farms and analysed for STEC O157:H7 by immunomagnetic separation methods and multiplex polymerase chain reaction for stx1 and/or stx2, the E. coli attaching and effacing (eae) and hly genes. STEC was detected in 26 of the 720 samples. The layer hens analysed were shown to carry STEC O157:H7. The presence of this bacterium in living layer hen farms investigated did not result in any detectable increase in gastrointestinal disease in this species. Living layer hens are a novel potential reservoir of E. coli O157:H7.