Katarzyna Przybyla-Kelly, Dawn A. Shively, and Muruleedhara N. Byappanahalli*
Not subject to U.S. Copyright. Published American Chemical Society
Incidence of the Enterococcal Surface Protein (esp) Gene in Human and Animal Fecal Sources
Richard L. Whitman,
Katarzyna Przybyla-Kelly, Dawn A. Shively, and Muruleedhara N. Byappanahalli*
U.S. Geological Survey, Great Lakes Science Center, Lake Michigan Ecological Research Station, 1100 Mineral Springs Road, Porter, Indiana 46304
Received for review April 6, 2007
Revised manuscript received June 18, 2007
Accepted July 2, 2007
Abstract:
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 (espfm)
and the other for both E. faecalis and E. faecium (espfs/fm).
We believe that this research is the first to explore the use of espfs/fm
for the detection of human waste in natural environmental settings. The
incidence in human sources was 93.1% espfm and 100% espfs/fm
in raw sewage influent; 30% for both espfm and espfs/fm
in septic waste; and 0% espfm and 80% espfs/fm
in active pit toilets. The overall occurrence of the gene in animal feces
was 7.7% (espfs/fm) and 4.7% (espfm);
animal types with positive results included dogs (9/43, all espfm),
gulls (10/34, espfs/fm; 2/34, espfm),
mice (3/22, all espfs/fm), and songbirds (5/55, all espfs/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 espfs/fm
were common in raw sewage, but neither one efficiently differentiated between
animal and other human sources.
Richard Whitman
Research Ecologist/Station Chief
Lake Michigan Ecological Research Station
219-926-8336 Ext. 424
1100 North Mineral Springs Road
Porter, IN 46304