Assessment of Microbiological Safety of Water in Public Swimming Pools in Guangzhou, China.

This study assessed microbiological safety of water from public swimming pools in Guangzhou, China. Water samples from 39 outdoor municipal swimming pools were collected from late June to early September, 2013 and subjected to detection of protozoa ( and ) and bacteria (, total coliforms, , O157, , and ). and were both detected in 5 (12.8%) swimming pools. Total coliforms were detected in 4 (10.3%) samples with concentrations ranging from 1.3 to 154.0 MPN/100 mL while was detected in 4 (10.3%) samples with concentrations ranging from 0.5 to 5.3 MPN/100 mL. was detected in 27 (69.2%) samples but O157, and were not detected. Among these swimming pools, 9 (23%) met the Chinese National Standard of residual chlorine levels and 24 (62%) were tested free of residual chlorine at least once. The multi-locus sequence typing (MLST) analysis showed that all isolates belonged to new sequence types (STs) with dominant ST-1764 and ST-D distributed in different locations within the area. Some strains were resistant to medically important antibiotics. Results indicate potential public health risks due to the presence of microbiological pathogens in public swimming pools in this area.