Occurrence and distribution of Antibiotics and Antibiotic-Resistant Bacteria in the Suquía River (Córdoba, Argentina).

VALDÉS, M.E.; RUIZ SMANIA, M.; SANTOS, LUCÍA HELENA; BARCUDI, DANILO; RODRIGUEZ CASTRO, CAROLINA; GIORGI, ADONIS; WUNDERLIN, D. A.; BARCELÓ D; BASTIDA, J.; SAKA, HECTOR A.; RODRIGUEZ-MOZAZ, S; AMÉ, MARÍA VALERIA

Toronto

Congreso; XXº Congress SETAC Northamerica; 2019

SETAC NA

Antibiotics (AB) are a particular group of emerging contaminants that have gained a lot of attention because of their high consumption in human and veterinary medicine, worldwide distribution in the environment, in addition to association with the proliferation of antibiotic resistance bacteria (ARB), bearing clinically relevant antibiotic resistance genes (ARG). The aim of this study was evaluating the presence and environmental distribution of both AB and ARB in the urban area of Suquía River (Córdoba city-1,330,023 inhabitants, Argentina). Samples of water, sediment and natural river biofilms were collected at 5 sampling points: S1- control (upstream Córdoba city and the intake of water supply), S2 (dump area), S3 (downstream a city ring way), S4 and S5 (6 and 10 km downstream the city wastewater treatment plant-WWTP-discharge), during wet and dry seasons (2016). Samples were extracted by SPE, PLE and bead disruption. AB residues were determined by UPLC-MS/MS analysis: 50 compounds in water, 40 in biofilm and 30 in sediments. Water samples were also cultured in selective chromogenic media for detection of ARB. As a result, 12 AB belonging to 8 chemical families were quantified in samples of urban influence (S2 to S5): 0.003-292 µg/L in water, 2-652 µg/kg d.w. in biofilm, and 0.6-34 µg/kg d.w. in sediment. No AB were detected in S1. S4 and S5 were the most polluted sites, showing the highest loads and variety of AB. However, non-point sources of pollution in S2 and S3 were evident. Cephalexin was the most frequent AB in water samples, while fluoroquinolones (ofloxacin and ciprofloxacin), in addition to macrolides (clarithromycin and azithromycin), were the most frequent AB in biofilms and sediments. This correlated with marked enrichment in ARB bearing clinical relevant ARGs, such us extended-spectrum producing Enterobacteriaceae and glycopeptide resistant Enterococcus. Higher AB frequencies and concentrations were detected in solid matrixes during wet season. This could be related to matrixes composition: more heterotrophic communities in biofilms, and higher organic carbon content in sediments. The presence of AB along the urban area of Suquía river points out wastewater treatment plant discharges as the main source of these compounds, while urban runoff and illegal sewage discharges increased the presence of AB in other areas. This study contributes to the knowledge of distribution of AB and their potential risk in urban impacted freshwater systems in South America.