Occurrence and distribution of antibiotics and antibiotic-resistant bacteria in the Suquía River (Córdoba, Argentina)

VALDÉS, M. E.; S. E. RUIZ; L. SANTOS; C. RODRIGUEZ-CASTRO; GIORGI ADONIS; D. A. WUNDERLIN; D. BARCELO; C. SOLA; H.A. SAKA; S. RODRIGUEZ-MOZAZ; M. V. AME

Toronto

Congreso; SETAC North America 40th Annual Meeting; 2019

SETAC NORTH AMERICA

Antibiotics (AB) are a particular group of emerging contaminants thathave gained a lot of attention because of their high consumption in humanand veterinary medicine, worldwide distribution in the environment, inaddition 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 distributionof both AB and ARB in the urban area of Suquia River (Cordobacity-1,330,023 inhabitants, Argentina). Samples of water, sediment andnatural river biofilms were collected at 5 sampling points: S1- control(upstream Cordoba city and the intake of water supply), S2 (dump area),S3 (downstream a city ring way), S4 and S5 (6 and 10 km downstream thecity wastewater treatment plant-WWTP-discharge), during wet and dryseasons (2016). Samples were extracted by SPE, PLE and bead disruption.AB residues were determined by UPLC-MS/MS analysis: 50 compoundsin water, 40 in biofilm and 30 in sediments. Water samples were alsocultured in selective chromogenic media for detection of ARB. As aresult, 12 AB belonging to 8 chemical families were quantified in samplesof 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 inS1. S4 and S5 were the most polluted sites, showing the highest loads andvariety of AB. However, non-point sources of pollution in S2 and S3 wereevident. Cephalexin was the most frequent AB in water samples, whilefluoroquinolones (ofloxacin and ciprofloxacin), in addition to macrolides(clarithromycin and azithromycin), were the most frequent AB inbiofilms and sediments. This correlated with marked enrichment in ARBbearing clinical relevant ARGs, such us extended-spectrum producingEnterobacteriaceae and glycopeptide resistant Enterococcus. Higher ABfrequencies and concentrations were detected in solid matrixes during wetseason. This could be related to matrixes composition: more heterotrophiccommunities in biofilms, and higher organic carbon content in sediments.The presence of AB along the urban area of Suquia river points out wastewatertreatment plant discharges as the main source of these compounds,while urban runoff and illegal sewage discharges increased the presenceof AB in other areas. This study contributes to the knowledge of distributionof AB and their potential risk in urban impacted freshwater systemsin South America.