Nuozzi, Guillermina; Chinen, Isabel; Miliwebsky, Sandra Elizabeth; Bianchelli, Julieta; Manfredi, Eduardo; Sagua, Mara; Schesi, Clara Florencia; Latorre, Daiana; Maiztegui, Cynthia Gabriela; Gentiluomo, Jimena; Carbonari, Carolina; Quiroga, María Pía; Schiaffino, María Romina
Resumen:
Many surface water systems are impacted by point source pollution from sewage discharges and industrial wastes, as well as
diffuse pollution from agriculture and livestock farming, inducing a potential biohazard to human, animal, and environmental
health. This study aimed to determine the presence of diarrhoeagenic Escherichia coli (DEC) pathotypes and their antibiotic
resistance, as well as the bacteriological, physical, and chemical water quality conditions in two Pampean peri-urban rivers
(Rojas and Salado rivers, Buenos Aires, Argentina) used for recreation. Additionally, we explored the impact of the surrounding
land use on the water quality. In the Rojas (R) and Salado (S) rivers, wastewater discharges from treatment plants increased
nutrient content and coliform abundances at specific sampling sites (R2 and S3) and downstream (R3 and S4, respectively).
Coliform abundances correlated with ammoniacal nitrogen concentrations, both exceeding recreational use guidelines. Out
of 36 samples positive for DEC virulence factors, 11 DEC strains were isolated (5 enteroaggregative, 3 enteropathogenic, 1
shigatoxigenic-stx1/stx2, 1 shigatoxigenic-stx2, 1 hybrid enteroaggregative-enterotoxigenic). Six strains were resistant to one
or more antibiotics. Our results suggest that differences in E. coli pathotypes between the two rivers and the water quality of
each sampling site are linked to the surrounding land use, evidencing both diffuse and point source pollution.
