ABSTRACT
The objective of this paper was to assess bacteriological quality of drinking water in a peri-urban area located in the Metropolitan Region of São Paulo, Brazil. A total of 89 water samples were collected from community plastic tanks and 177 water samples from wells were collected bimonthly, from September 2007 to November 2008, for evaluating bacteriological parameters including: Escherichia coli, Enterococcus and heterotrophic plate count (HPC). Clostridium perfringens was investigated in a subsample (40 samples from community plastic tank and 40 from wells). E. coli was present in 5 (5.6 percent) samples from community plastic tanks (2.0 - 5.1x10(4) MPN/100mL) and in 70 (39.5 percent) well samples (2.0 - 8.6x10(4) MPN/100mL). Thus, these samples were not in accordance with the Brazilian Regulation. Enterococcus was detected in 20 (22.5 percent) samples of the community plastic tanks (1 to 79 NC/100mL) and in 142 (80.2 percent) well samples (1 to >200 NC/100mL). C. perfringens was detected in 5 (12.5 percent) community plastic tanks samples and in 35 (87.5 percent) wells samples (2.2 to >16 MPN/100mL). HPC were above 500 CFU/mL in 5 (5.6 percent) waters from community plastic tanks. In wells samples, the HPC ranged from <1 to 1.6x10(4) CFU/mL. The residual chlorine did not attend the standard established in the drinking water legislation (0.2 mg/L), except in 20 (22.5 percent) samples. These results confirm the vulnerability of the water supply systems in this peri-urban area what is clearly a public health concern.
ABSTRACT
Aeromonas genus is considered an emerging pathogen and its presence in drinking water supplies is a reason to public health concern. This study investigated the occurrence of Aeromonas in samples from collective reservoirs and wells used as drinking water sources in a peri-urban area. A total of 35 water samples were collected from collective reservoirs and 32 from wells bimonthly, from September 2007 to September 2008. Aeromonas spp determination was carried out using a Multiple-Tube Technique. Samples were inoculated into alkaline peptone water and the superficial film formed was transferred to blood agar plates amended with ampicillin. Typical Aeromonas colonies were submitted to a biochemical screening and then to biochemical tests for species differentiation. Aeromonas was detected in 13 (19 percent) of the 69 samples examined (6 from collective reservoirs and 7 from wells). Concentrations of Aeromonas in collective reservoirs ranged from <0.3 to 1.2 x10²MPN/100mL and, in wells, from <0.3 to 2.4 x10²MPN/100mL. The most frequent specie in the collective reservoir samples was Aeromonas spp (68 percent), followed by A. encheleia (14 percent) and A. allosaccharophila (8 percent) and A. hydrophila (8 percent). Aeromonas spp (87 percent) was the most frequent specie isolated from well samples, followed by A. allosacchariphila (8 percent), A. encheleia (2 percent) and A. jandaei (5 percent). These data show the presence and diversity of Aeromonas genus in the samples analyzed and highlight that its presence in drinking water poses a significant public health concern.