Enteropathogenic Escherichia coli (EPEC) previously were identified in poult enteritis–mortality syndrome (PEMS)-affected turkeys and associated as a cause of this disease. In the present study, the prevalence of EPEC in PEMS-affected turkeys was examined retrospectively with archived tissues and intestinal contents collected from 12 PEMS-affected turkey flocks in 1998. Formalin-fixed intestinal tissues were examined by light and electron microscopy for attaching and effacing (AE) lesions characteristic of EPEC, and frozen (−75 C) intestinal contents were examined for presence of EPEC. Escherichia coli isolates were characterized on the basis of epithelial cell attachment, fluorescent actin staining (FAS) test, and presence of E. coli attaching/effacing (EAE), shigalike toxin (SLT) type I, SLT II, and bundle-forming pilus (BFP) genes by polymerase chain reaction procedures. EPEC isolates were examined for pathogenicity and ability to induce AE lesions in experimentally inoculated young turkeys.
AE lesions were identified by light microscopy in Giemsa-stained intestines from 7 of 12 PEMS-affected turkey flocks. Lesions consisted of bacterial microcolonies attached to epithelial surfaces with epithelial degeneration at sites of attachment and inflammatory infiltration of the lamina propria. Electron microscopy confirmed the identity of AE lesions in six of seven flocks determined to have AE lesions by light microscopy. EPEC were identified in 4 of 12 flocks on the basis of the presence of EAE genes and absence of SLT I and SLT II genes; all isolates lacked BFP genes. EPEC isolates produced AE lesions and variable mortality in turkeys coinfected with turkey coronavirus. In total, EPEC were associated with 10 of 12 (83%) naturally occurring PEMS cases on the basis of identification of AE lesions and/or EPEC isolates. These findings provide additional evidence suggesting a possible role for EPEC in the pathogenesis of PEMS.