Incidence of the enterococcal surface protein (esp) gene in human and animal fecal sources

The occurrence of the enterococcal surface protein (esp) gene in the opportunistic pathogens Enterococcus faecalis and E faecium is well-documented in clinical research. Recently, the esp gene has been proposed as a marker of human pollution in environmental waters; however, information on its relative incidence in various human and animal fecal sources is limited. We have determined the occurrence of the esp gene in enterococci from human (n = 64) and animal (n = 233) fecal samples by polymerase chain reaction using two primer sets: one presumably specific for E faecium (esp(fm)) and the other for both E. faecalis and E faecium(esp(fs/fm)). We believe that this research is the first to explore the use of esp(fs/fm) for the detection of human waste in natural environmental settings. The incidence in human sources was 93.1% esp(fm) and 100% esp(fs/fm) in raw sewage influent; 30% for both esp(fm) and esp(fs/fm) in septic waste; and 0% espfm and 80% esp(fs/fm), in active pit toilets. The overall occurrence of the gene in animal feces was 7.7% (esp(fs/fm)) and 4.7% (espf,); animal types with positive results included dogs (9/43, all esp(fm)), gulls (10/34, esp(fs/fm),; 2/34, esp(fm), mice (3/22, all esp(fs/fm)), and songbirds (5/55, all esp(fs/fm)). The esp gene was not detected in cat (0/34), deer (0/4), goose (0/18), or raccoon (0/23) feces. The inconsistent occurrence, especially in septic and pit toilet sewage, suggests a low statistical power of discrimination between animal and human sources, which means a large number of replicates should be collected. Both espfm and esp(fs/fm), were common in raw sewage, but neither one efficiently differentiated between animal and other human sources.