Abundance of antibiotic resistance genes in five municipal wastewater treatment plants in the Monastir Governorate, Tunisia.
Antimicrobial resistance is a growing and significant threat to global public health, requiring better understanding of the sources and mechanisms involved in its emergence and spread. We investigated the abundance of antibiotic resistance genes (ARGs) before and after treatment in five wastewater treatment plants (WWTPs) located in different areas of the Monastir Governorate (Tunisia). Three of these WWTPs (Frina, Sahline and Zaouiet) use a conventional activated sludge process as secondary treatment, whereas the WWTP located in Beni Hassen applies an ultraviolet disinfection step after the activated sludge process and the WWTP located in Moknine treats wastewater using naturally aerated lagoons as a secondary treatment process. The abundance of six ARGs (blaCTX-M, blaTEM, qnrA, qnrS, sul I and ermB) and the class 1 integron-integrase gene (intI1) were determined by quantitative PCR. All ARGs and the intI1 gene were detected in the wastewater samples, except the blaCTX-Mgene, which was not detected in both influent and effluent samples from Sahline and Beni Hassen WWTPs, and the qnrS gene, which was not detected neither in the WWTP influent in Moknine nor in the WWTP effluent in Beni Hassen. Although the relative concentration of ARGs was generally found to be similar between samples collected before and after the wastewater treatment, the abundance of blaCTX-M, blaTEM, and qnrS genes was higher in the effluent of the Frina WWTP which, unlike other WWTPs, not only receives domestic or industrial sewage but also untreated hospital waste. To the best of our knowledge, this study quantified for the first time the abundance of ARGs in different Tunisian WWTPs, and the results agree with previous studies suggesting that conventional wastewater treatment does not efficiently reduce ARGs. Therefore, these findings could be useful to improve the design or operation of WWTPs.
Laboratory of Transmissible Diseases and Biologically Active Substances, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia; Higher Institute of Biotechnology of Monastir, Monastir, Tunisia.
Ikbel Denden
ID
Rafraf
Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
Itziar
I
Lekunberri
Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain.
Alexandre
A
Sànchez-Melsió
Laboratory of Transmissible Diseases and Biologically Active Substances, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia.
Mahjoub
M
Aouni
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.
Carles M
CM
Borrego
Catalan Institute for Water Research (ICRA), Scientific and Technological Park of the University of Girona, Girona, Spain. Electronic address: jlbalcazar@icra.cat.
José Luis
JL
Balcázar
D000900:Anti-Bacterial Agents / Q000032:analysis*; D002947:Cities; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial / Q000187:drug effects*; D032023:Integrons; D012722:Sewage / Q000737:chemistry*; D014416:Tunisia; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis*
D000900:Anti-Bacterial Agents; D012722:Sewage; D062065:Wastewater
Antibiotic resistance genes; Treatment processes; Urban wastewater