Environmental Impact on Levels of Pathogenic Indicator Microorganisms in Water Streams.

Presence and persistence of pathogenic microorganism in water streams can be attributed to presence of input sources and to physiological pressures due to external (environmental) conditions, the most noteworthy of the latter being pH, temperature, electroconductivity (EC), redox potential, dissolved oxygen and total dissolved solids (TDS). The use of E. coli as an indicator microorganism for pathogenic contamination has been in practice for some time now. This experiment set out to do to test the significance of background concentrations and the impact of presence of grazing cattle on the water quality in a small creek had on the levels of E. coli, Salmonella, fecal enterococci, Clostridium perfringens, and Salmonella. Collection of water samples, taken at sites along a 5 km long creek in Eastern Ontario, Canada was carried over the warm season (May to September) from 2005 to 2007. The significance of the mentioned environmental factors was examined; it was found that E. coli counts where highly correlated to changes in pH, temperature and less so TDS. There was little impact attributable to the presence of grazing cattle along a 1km segment of the creek. However the E. coli counts did not correlate with the counts in the headwaters. This may suggest that while some transfer of E. coli may occur from the headwaters downstream, the E. coli numbers are significantly influenced by phenomena occurring at individual creek segments. Moreover, preliminary antibiotic resistant gene survey showed that antibiotic resistant to betalactams, glycopeptides, erytromycin, tetracycline and fluoroquinolone was present downstream from animal grazing locations and not present in the head waters. C. perfringens counts variation in successive creek segments was less significant and less affected by local variations in water flow and quality parameters. Quality of headwaters and local environmental impacts did control bacterial counts more than identified potential contamination sources.