Occurrence and persistence of antibiotic resistance genes in river biofilms after wastewater inputs in small rivers

Lorenzo Proia; Daniel von Schiller; Alexandre Sànchez-Melsió; Sergi Sabater; Carles M Borrego; Sara Rodríguez-Mozaz; José Luis Balcázar

doi:10.1016/j.envpol.2015.11.035

Occurrence and persistence of antibiotic resistance genes in river biofilms after wastewater inputs in small rivers

Environ Pollut. 2016 Mar:210:121-8. doi: 10.1016/j.envpol.2015.11.035. Epub 2015 Dec 18.

Authors

Lorenzo Proia¹, Daniel von Schiller², Alexandre Sànchez-Melsió³, Sergi Sabater⁴, Carles M Borrego⁵, Sara Rodríguez-Mozaz³, José Luis Balcázar³

Affiliations

¹ Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain; Institute of Aquatic Ecology, GRECO, University of Girona, Girona, Spain. Electronic address: proialorenzo@hotmail.it.
² Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country, Bilbao, Spain.
³ Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
⁴ Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain; Institute of Aquatic Ecology, GRECO, University of Girona, Girona, Spain.
⁵ Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain; Group of Molecular Microbial Ecology, Institute of Aquatic Ecology, University of Girona, Girona, Spain.

PMID: 26708766
DOI: 10.1016/j.envpol.2015.11.035

Abstract

The extensive use of antibiotics in human and veterinary medicine and their subsequent release into the environment may have direct consequences for autochthonous bacterial communities, especially in freshwater ecosystems. In small streams and rivers, local inputs of wastewater treatment plants (WWTPs) may become important sources of organic matter, nutrients and emerging pollutants, such as antibiotic resistance genes (ARGs). In this study, we evaluated the effect of WWTP effluents as a source of ARGs in river biofilms. The prevalence of genes conferring resistance to main antibiotic families, such as beta-lactams (blaCTX-M), fluoroquinolones (qnrS), sulfonamides (sul I), and macrolides (ermB), was determined using quantitative PCR (qPCR) in biofilm samples collected upstream and downstream WWTPs discharge points in four low-order streams. Our results showed that the WWTP effluents strongly modified the hydrology, physico-chemistry and biological characteristics of the receiving streams and favoured the persistence and spread of antibiotic resistance in microbial benthic communities. It was also shown that the magnitude of effects depended on the relative contribution of each WWTP to the receiving system. Specifically, low concentrations of ARGs were detected at sites located upstream of the WWTPs, while a significant increase of their concentrations was observed in biofilms collected downstream of the WWTP discharge points (particularly ermB and sul I genes). These findings suggest that WWTP discharges may favour the increase and spread of antibiotic resistance among streambed biofilms. The present study also showed that the presence of ARGs in biofilms was noticeable far downstream of the WWTP discharge (up to 1 km). It is therefore reasonable to assume that biofilms may represent an ideal setting for the acquisition and spread of antibiotic resistance determinants and thus be considered suitable biological indicators of anthropogenic pollution by active pharmaceutical compounds.

Keywords: Antibiotic resistance; Biofilms; Genes; Rivers; WWTPs.

MeSH terms

Anti-Bacterial Agents / analysis
Anti-Bacterial Agents / toxicity
Biofilms*
Drug Resistance, Microbial / genetics*
Rivers / chemistry*
Wastewater / chemistry*

Substances

Anti-Bacterial Agents
Waste Water