ENTEROCOCCI SPECIES IN GULF COAST MARINE WATER SAMPLES AS MEASURED BY THE ENVIRONMENTAL PROTECTION AGENCY METHOD 1600

摘要

Enterococcus density, as determined by the United States Environmental Protection Agency Method 1600, is used as an index of fecal pollution in marine waters. To determine the range of fecal and non-fecal enterococci species captured by the assay, seawater samples were collected in 2004 at six locations along twelve miles of southeast Texas coastline over a five month period. Using USEPA Method 1600, ninety one confirmed enterococcus isolates were recovered. Differential sugar and sugar alcohol fermentation patterns were used to identify the species of each isolate. Fecal enterococci species (E. faecalis/E. avium, E. faecium, E. gallinarum) accounted for only 52 percent of the confirmed enterococcus isolates. Another 45 percent of the isolates were environmental enterococci (E. raffinosus, E. mundtii, E. hirae, E. dispar, E. durans, E. malodoratus, E. pseudoavium). Three percent of the isolates could not be identified as a known species. These data show that the current method used to measure enterococcus density in sub-tropical marine waters fails to differentiate between fecal and environmental enterococcus species. Therefore, the USEPA Method 1600 may yield erroneous data concerning recreational water quality.