Aeromonas species are autochtonous in the aquatic environment and some of them have been associated with health effects like wound infections, septicemia and diarrhoeal illness. In this study, the occurrence of Aeromonas spp. and microbial indicators in raw drinking water from wells, springs, fountains and mineral waters was evaluated. A total of 126 water samples was analyzed for Aeromonas spp. by the membrane filtration technique using ADA media and by P/A test. Typical colonies of Aeromonas spp. were submitted to biochemical tests for species differentiation. Toxin production was tested using Y-1 mouse adrenal cells. Coliforms and heterotrophic bacteria were enumerated by membrane filtration and pour plate techniques, respectively. P. aeruginosa, C. perfringens and fecal streptococci were determined by P/A method. Aeromonas spp. were isolated in 36.5% of the samples, whereas total and thermotolerant coliforms were detected in 51.2% and in 23.8% of the samples, respectively. C. perfringens, fecal streptococci and P. aeruginosa were present in 16.5%, 20.4% and 3.8% of the samples, respectively. The concentrations of heterotrophic bacteria were higher than 1,0x10³ CFU/mL in 52.5% of the samples. A. hydrophila was the most frequent species, followed by A. allosaccharophila,A. jandaei,A.sobria and HG2. A heat label toxin was detected in 13 from the 58 strains tested. These data show that the drinking water sources analyzed can represent a risk for human health. It is important to consider that wells and springs are used as drinking water supply in poor areas and rural regions, where undernourished people more susceptible to infections by these microorganisms predominate.
Aeromonas; raw drinking water; microbial indicators; heat labile toxin
