Q-233. Evaluation of Intimin and Bundle-Forming Pilus in Environmental Escherichia coli

L. Bauer, E. W. Alm;
Central Michigan Univ., Mount Pleasant, MI.

Pathogenicity of enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) is determined in part by their ability to attach to host epithelial cells via the attachment proteins bundle-forming pilus (EPEC) and intimin (EPEC and EHEC). We have screened DNA extracts from 121 E. coli isolated from beach sand and have observed eae, the gene that encodes intimin, in 78% of isolates, and bfp, the gene that encodes bundle-forming pilus, in 34%. As bundle-forming pilus and intimin are associated with pathogenicity of E. coli pathotypes, such high frequencies of bfp and eae in the beach sand environment is surprising, unless the proteins they encode are necessary for a survival function in this environment. Recent studies indicate that certain populations of E. coli may be adapted for long-term survival in beach sand; attachment to sand particles may be necessary for such persistence. The goal of this study is to explore the potential roles bundle-forming pilus and intimin play in attachment in a “naturalized” population of E. coli versus attachment of E. coli isolated from humans, cattle, ducks, or gulls. A three-tiered approach is being used in this study. Isolates were initially screened for the presence of bfp and eae using two separate PCR reactions. Of the 256 isolates screened, 18 were positive for eae, while bfp was detected in 8. The presence of eae and bfp in the beach naturalized isolates indicates a potential that their corresponding attachment proteins may aid in survival in the beach sand environment. Western blot analysis indicates none of the isolates positive by PCR for bfp are actually expressing the protein, and analysis of eae positive samples is currently underway. Isolates expressing attachment proteins will be incubated in sterile beach sand and viewed using immunofluorescence microscopy to determine if they are using bundle-forming pilus and/or intimin for attachment to sand. Results of this study will provide insight into whether proteins associated with E. coli pathotype attachment are aiding E. coli persistence in beach environments and potential public health implications of naturalized E. coli at recreational beaches.