Comparative studies on Enterococcus, Clostridium perfringens and Staphylococcus aureus as quality indicators in tropical seawater at a Pacific Mexican beach resort

Three microorganisms were assayed to evaluate the microbiological quality in the seawater at a resort on the Mexican Pacific coast, and to test for possible associations among the titers of the various bacteria, their possible correlations with environmental conditions, and with the location of potential wastewater outflows. Significant microorganism levels were found (at Caletilla beach, Hornos beach, and Papagayo beach, respectively: for Enterococcus 157, 153, and 149, for C. perfringens 35, 89, and 56, for S. aureus 244,137, and 279 CFU/100 ml), often in excess of the presently set guideline values. In general, bacterial titers were higher during rainy season than in dry season. For S. aureus, in both seasons, highest concentrations were found at 3 pm, the time of highest tourist presence at the beaches. Our results argue for the use of these three microorganisms as part of a set of indicators in the routine microbiological evaluation of Mexican beachwaters.