Water is indispensable for life and its quality is directly related to public health. The objective of this study was to investigate the presence of Pseudomonas aeruginosa in public water supply in municipalities in São Paulo State, Brazil. Analyses were carried out at the Adolfo Lutz Institute between February and December 2016, and included physicochemical (chlorine, pH, color, turbidity and nitrate), and microbiological parameters (total coliforms and Escherichia coli), as well as P. aeruginosa, with susceptibility tests to antimicrobial agents and biofilm production capacity by the strains isolated. In total, 251 water samples were evaluated and 19 (7.6%) presented P. aeruginosa. No significant differences were observed between the physicochemical parameters found in the positive and negative samples for this bacterium, but the samples containing total coliforms were also those with the highest positivity for P. aeruginosa. All samples with P. aeruginosa reported chlorine concentrations between 0.2 and 2.0 mg/L, as required by Brazilian legislation, demonstrating this bacterium's resistance to conventional water treatment processes. Although not resistant to the antimicrobials tested, most strains isolated were classified as strong biofilm producers, emphasizing the need for further studies involving water supply quality.

Aims To evaluate the physicochemical and microbiological quality of dialysis water and dialysate samples from haemodialysis centres. Methods and Results Samples were fortnightly collected from three haemodialysis centres in Bauru City, Brazil, between July 2017 and June 2018, at the stages of post‐reverse osmosis, reuse and dialysate. Analyses included determination of conductivity, fluoride, nitrate and sulphate; test for total coliform bacteria; count of heterotrophic bacteria; count and identification of non‐fermenting gram‐negative bacilli (NFGNB); drug susceptibility test; biofilm formation capacity; and genetic similarity among some isolated NFGNB. Of the analysed samples, only 4/72 (5.6%) had conductivity values ≥10 mS/cm, 4/216 (1.9%) presented total coliforms and 1/216 (0.5%) had heterotrophic bacteria count >100 CFU/ml. NFGNB were isolated from 99/216 (45.8%) samples, and the major identified micro‐organisms included Herbaspirillum aquaticum/huttiense, Brevundimonas aurantiaca, Cupriavidus metallidurans, Pseudomonas aeruginosa and Ralstonia insidiosa. Isolates of P. aeruginosa and Burkholderia cepacia complex were sensitive to most antimicrobials and, together with isolates of Ralstonia insidiosa and Ralstonia pickettii, showed strong biofilm formation capacity. Some isolates expressed the same electrophoretic profile on pulsed‐field gel electrophoresis, indicating the persistence of bacterial clones in the systems over time. Conclusions NFGNB were observed in several dialysis water and dialysate samples from all investigated centres, which may represent a risk to the health of patients. Significance and Impact of the Study Regular inclusion of actions for NFGNB control and monitoring in haemodialysis fluids are suggested for greater safety of the dialytic process.