Occurrence of enterococci harbouring clinically important antibiotic resistance genes in the aquatic environment in Gauteng, South Africa

• Published in: Environmental pollution (1987) 2019-02, Vol.245, p.1041-1049
• Main Authors: Hamiwe, Thabo, Kock, Marleen M., Magwira, Cliff A., Antiabong, John F., Ehlers, Marthie M.
• Format: Article
• Language: English
• Subjects: Antibiotic resistance genes; Enterococcus; Wastewater; Water sources
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2018.11.040

The development of antibiotic resistance and dissemination of its determinants is an emerging public health problem as it compromises treatment options of infections that were, until recently, treatable. Investigation of outbreaks of vancomycin resistant enterococci (VRE) suggests that the environment serves as a significant reservoir for antibiotic resistance genes (ARGs). However, there is a paucity of data regarding the presence of ARGs in the water sources in South Africa. In this study, water samples collected from wastewater treatment plants (WWTPs), surface water and hospital sewage were screened for enterococci harbouring genes conferring resistance to four classes of antibiotics. Enterococci isolates harbouring ARGs were detected in raw influent and treated wastewater discharge from WWTPs and hospital sewage water. Plasmid and transposon encoded ermB (macrolide), tetM and tetL (tetracycline) as well as aph(3’)-IIIa (aminoglycosides) genes were frequently detected among the isolates, especially in E. faecalis. The presence of enterococci harbouring ARGs in the treated wastewater suggest that ARGs are discharged into the environment where their proliferation could be perpetuated. Among the enterococci clonal complexes (CCs) recovered from wastewater were E. faecium CC17 (ST18), which is frequently associated with hospital outbreaks and a novel E. faecalis sequence type (ST), ST780. [Display omitted] •Various sewage wastewater and surface water samples were assayed for enterococci harbouring clinically relevant antibiotic resistance genes.•Enterococcus faecalis was the most prevalent enterococci in the wastewater.•ermB, tetM, tetL as well as aph(3‘)-IIIa resistance genes were frequently detected in the enterococci isolates.•Wastewater treatment plants showed moderate removal of enterococci harbouring ARG. Enterococci harbouring clinically relevant antibiotic resistance genes detected in South African water sources.