Detection of Shiga toxin-producing Escherichia coli O157 in living layer hens.

The present report was undertaken with the aim to evaluate the presence of Shiga toxin-producing Escherichia coli (STEC) of the O157 serotype in living layer hens to analyse the role of this avian species as potential reservoir. This study was carried out between January 2004 and September 2004 on three intensive management layer hen farms (named A, B, C) in the Campania Region (Southern Italy). 60 cloacal swabs were collected from each farm. A total of 180 cloacal swabs were obtained. All cloacal swab samples were enriched 1:10 in 10 ml of modified Tryptone Soy Broth supplemented with novobiocin and incubated at 41 ± 1 °C, for 12-18 h. Subsequently, immunomagnetic separation (IMS) was done. After IMS, the solution was inoculated onto sorbitol MacConkey agar supplemented with cefixime-tellurite and Chromogenic E. coli O157 Agar. Suspected E. coli O157 colonies were tested by agglutination with an E .coli O157 latex test kit for confirmation. E. coli O157 isolates were screened for possession of genes encoding for the stx1 and stx2, the E. coli attaching-and-effacing (eae) and hly genes. A polymerase chain-reaction (PCR) with the use of established primers was used. STEC was detected in 13 (three from farm A and ten from farm C) of the total 180 samples. All isolates from farm A and farm C carried eae and stx2 genes. Two isolates from farm A and eight isolates from farm C carried stx1 gene. Additionally, all isolates from farm A and six isolated from farm C carried hly gene. In contrast, all isolated from Farm B were negative for STEC. To our knowledge the present report is the first isolating STEC in living layer hens in Italy. All layer hens analysed in our report were apparently in a healthy body condition and which emphasised our hypothesis about their potential role as reservoir hosts for STEC O157. _____________________________________________________________________________________