ANALYSIS OF THE VIRULENCE CHARACTERISTICS OF BACTERIA ISOLATED FROM BOTTLED, WATER-COOLER, AND TAP WATER

A study was conducted to determine the numbers and types of bacteria f ound in three water sources-bottled water, water cooler water, and tap water-and to determine their virulence characteristics. A wide variet y of water types were collected and each was analysed for Heterotrophi c Plate Count (HPC) bacteria, Pseudomonas aeruginosa, and total colifo rms. For each isolate, virulence characteristics were determined by en zyme analysis (10 associated with virulence), antibiotic susceptibilit y testing (natural and semi-synthetic antibiotics), acid lability (sur vival at pH 3.5), and cytotoxicity testing (HEp-2 cells). Results show ed that all water sources had a normal bacterial content. Only 2 per c ent of bottled water sources had P, aeruginosa. Total coliforms were i solated only from bottled water that used mixed (water alternating wit h milk) filling lines. Environmental bacteria did not produce signific ant enzymes associated with virulence, were not acid resistant, were s usceptible to semi-synthetic antibiotics, and did not produce apprecia ble cytotoxicity. These natural aqueous bacteria were adopted to a wat er environment, did not grow well at conditions analogous to the human host, and did not have the characteristics associated with virulence. Future drinking water revisions and changes to the treatment processe s should be directed towards the elimination of specific pathogens and to the prevention of exogenous sources of contamination rather than t he elimination of natural water microbial populations.