Evaluation of enterococcal surface protein genes as markers of sewage contamination in tropical recreational waters

A molecular monitoring strategy was developed to detect prevalence of two enterococcal surface protein genes (esp-1 gene and esp-2 gene) in isolates of enterococci from recreational waters in Hawaii as evidence of human sewage contamination. The sensitivity and specificity of the methods were evaluated in selected environmental samples including human sewage, ocean water samples near a sewage outfall, shoreline coastal beach waters, ambient soil samples and ambient streams not known to be contaminated with sewage. The results of this study show that the esp-1 and esp-2 genes are highly associated with enterococci from sewage sources as compared to non-point sources. Therefore these esp genes show promise as good indicators of sewage contamination. However, more sensitivity and specificity of esp genes are needed. Moreover, a more specific enumeration method for E. faecium and E. faecalis is needed so that subsequent test for the esp genes will be reliable and feasible.