E. coli 0157:H7 were isolated from 0.86% (n=1520) water samples and Salmonella species from 6.04% (n=1456) samples collected within the Oldman River watershed in southern Alberta. Peak prevalence of E. coli0157:H7 in July 2000 was 6.3% (n=48). Peak prevalence of Salmonella was 16.2% (n=11) in August 1999 and 33.% (n=42) in July 2000. Prevalence was greater in water from some sampling locations than from others. In non-filtered surface water E. coli0157:H7 and S. typhimurium numbers decreased significantly faster at 20 degrees celsius than at 10 degrees celsius (P=0.000); however this difference did not exist when the same water was filtered (P=0.439). Pathogen survival in one water sample was greater when it was filtered (0.2um pore) than when it was not filtered even though there were no autochthonous bacteria in the water prior to filtration. / xi, 268 leaves ; 28 cm.

Metabolic were used to evaluate Enterococcus as an indicator of faecal pollution. Enterococci were isolated using m-Enterococcus agar and speciated using conventional biochemical tests. Forty percent of the isolates were identified and metabolically characterized by the automated Biolog system. The biochemical test scheme recognized 16 enterococcal species, while Biolog recognized nine. Both methods identified E. faecalis at the greatest frequency. Overall species frequencies varied between the two methods. Biolog was unable to identify 31% of the isolates; 7% of the isolates were unidentified by the biochemical test scheme. Of the identified isolates, metabolic profiling with Biolog achieved speciation with 60 substrates. Unique profiles were obtained for 89% of the isolates. Isolates also demonstrated inter-trial differntial metabolism of substrates. This and the large number of unidentified isolates suggest great diversity among enterococci. Diversity and inter-trial metabolic inconsistencies will complicate use of enterococcal metabolic profiles as a source-tracking tool. / xxiii, 264 leaves ; 29 cm.