[Isolation of antibiotic-resistant Escherichia coli from the water of the Río de la Plata].

Water of a recreational zone of the Río de la Plata was analyzed. Levels of total heterotrophic bacteria ranged from 1.5 x 10(3) to 6.2 x 10(3) CFU/ml and total coliforms were between 5.0 x 10(2) and 7.0 x 10(3) per 100 ml. Values of fecal coliforms were between 1.0 x 10(2) and 1.3 x 10(3) per 100 ml. Among 131 E. coli strains isolated, 20.6% of cephalothin resistance was found, followed by nitrofurantoin, ampicillin, sulfisoxazole and the trimethoprim sulfamethoxazole combination. Resistance to more than one antibiotic was found in 36.7% of the strains isolated and 9.2% were resistant to three or more antibiotics. Three strains resistant to four antibiotics and one resistant to five were isolated. The highest percentage of combined resistance occurred for the pairs cephalothin-nitrofurantoin and cephalothin-ampicillin.