Staphylococci as microbiological indicators to estimate the quality of swimming pool waters

Graduation date: 1988Previous studies have indicated that staphylococci have potential for\ud use as indicators of water quality in swimming pool and other recreational\ud waters. However, these organisms are not yet included in the official\ud guidelines for recreational water quality promulgated by health authorities.\ud The purpose of this study is to determine water quality of swimming pools\ud and spas using staphylococci as microbiological indicators.\ud On three occasions, between January and February 1988, water samples\ud were collected from 14 public, indoor, chlorinated swimming pools and\ud spas in Linn and Benton Counties. Any pool was considered unsanitary if\ud Staphylococcus aureus was isolated and identified using the protocol outlined\ud in the Standard Methods for the Examination of Water and Wastewater in\ud accordance with the Oregon State Health Division guidelines. The temperature,\ud water clarity, pH, free chlorine, and total alkalinity likewise were\ud measured for a more effective evaluation of the bacteriological results.\ud Based on the above criteria, Staphylococcus aureus was isolated and\ud identified in 33 percent of the swimming pools. The number of total coliforms\ud isolated from these pools were not any higher than the other pools.\ud Staphylococcus aureus was not recovered from water samples collected\ud from the spas.\ud Staphylococcal and coliform densities increased with decreasing concentration\ud of free chlorine, but the densities of both organisms increased\ud with increasing bathing load. However, no statistical significance was noted\ud from the correlations (p > 0.05).\ud The number of total staphylococci and total coliforms isolated from\ud the surface microlayer using the Millipore membrane filter was higher than\ud those obtained from the inlet and outlet sites. When these organisms were\ud correlated, a significant result was observed for the surface microlayer\ud (r = 0.5836, p = .01423), but not for the other two sampling sites (inlet and\ud outlet). Thus, the use of the membrane filter is a more effective means of\ud recovering these organisms.\ud Results of this study suggest that swimming pools that appear to be\ud well-maintained could harbor pathogenic organisms such as Staphylococcus\ud aureus. Furthermore, in comparison to coliforms, Staphylococcus aureus\ud was found to be a more sensitive indicator of recreational water quality.\ud Further investigations appear to be warranted to confirm these findings