[Mycobacteria in swimming pool water and the meaning of microbiological conventional indicators]

Monitoring program of hygienic quality water in twelve public swimming pools was performed. Legally required microbiological indicator parameters of safety for gastrointestinal illness were measured besides the analyses of Pseudomonas spp. and Staphylococcus spp. prevalence, frequency of recovery and number of nontuberculous mycobacteria. We detected positive samples for coliforms at lower rate (29.3%) than Pseudomonas (75.5%), Staphylococcus spp. (46%) and Mycobacteria (59.4%). We pointed out statistically significant correlation (r=0.67 p=0.0001) between Mycobacteria and Pseudomonas so we think that the latter might be a good predictive marker. As 82% of samples had free chlorine residual within the limits stated by Italian Laws, the efficacy of chlorination to prevent risk of infectious diseases transmission by route other than gastroenteric was discussed. A revision of both the sanitary significance of conventional microbial parameters and the related regulations appears necessary.