Molecular Typing Reveals Environmental Dispersion of Antibiotic-Resistant Enterococci under Anthropogenic Pressure

Anca Farkas; Cristian Coman; Edina Szekeres; Adela Teban-Man; Rahela Carpa; Anca Butiuc-Keul

doi:10.3390/antibiotics11091213

Molecular Typing Reveals Environmental Dispersion of Antibiotic-Resistant Enterococci under Anthropogenic Pressure

Antibiotics (Basel). 2022 Sep 7;11(9):1213. doi: 10.3390/antibiotics11091213.

Authors

Anca Farkas^{1

2}, Cristian Coman³, Edina Szekeres^{1

3}, Adela Teban-Man^{3

4}, Rahela Carpa^{1

2}, Anca Butiuc-Keul^{1

2}

Affiliations

¹ Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babeș-Bolyai University, 1 M. Kogălniceanu Street, 400084 Cluj-Napoca, Romania.
² Centre for Systems Biology, Biodiversity and Bioresources, Babeș-Bolyai University, 5-7 Clinicilor Street, 400006 Cluj-Napoca, Romania.
³ National Institute of Research and Development for Biological Sciences (NIRDBS), Institute of Biological Research, 48 Republicii Street, 400015 Cluj-Napoca, Romania.
⁴ Department of Taxonomy and Ecology, Faculty of Biology and Geology, Babeș-Bolyai University, 1 M. Kogălniceanu Street, 400084 Cluj-Napoca, Romania.

Abstract

As a consequence of global demographic challenges, both the artificial and the natural environment are increasingly impacted by contaminants of emerging concern, such as bacterial pathogens and their antibiotic resistance genes (ARGs). The aim of this study was to determine the extent to which anthropogenic contamination contributes to the spread of antibiotic resistant enterococci in aquatic compartments and to explore genetic relationships among Enterococcus strains. Antimicrobial susceptibility testing (ampicillin, imipenem, norfloxacin, gentamycin, vancomycin, erythromycin, tetracycline, trimethoprim-sulfamethoxazole) of 574 isolates showed different rates of phenotypic resistance in bacteria from wastewaters (91.9-94.4%), hospital effluents (73.9%), surface waters (8.2-55.3%) and groundwater (35.1-59.1%). The level of multidrug resistance reached 44.6% in enterococci from hospital effluents. In all samples, except for hospital sewage, the predominant species were E. faecium and E. faecalis. In addition, E. avium, E. durans, E. gallinarum, E. aquimarinus and E. casseliflavus were identified. Enterococcus faecium strains carried the greatest variety of ARGs (bla_TEM-1, aac(6')-Ie-aph(2″), aac(6')-Im, vanA, vanB, ermB, mefA, tetB, tetC, tetL, tetM, sul1), while E. avium displayed the highest ARG frequency. Molecular typing using the ERIC2 primer revealed substantial genetic heterogeneity, but also clusters of enterococci from different aquatic compartments. Enterococcal migration under anthropogenic pressure leads to the dispersion of clinically relevant strains into the natural environment and water resources. In conclusion, ERIC-PCR fingerprinting in conjunction with ARG profiling is a useful tool for the molecular typing of clinical and environmental Enterococcus species. These results underline the need of safeguarding water quality as a strategy to limit the expansion and progression of the impending antibiotic-resistance crisis.

Keywords: ERIC-PCR; Enterococcus avium; Enterococcus faecalis; Enterococcus faecium; antimicrobial resistance; freshwater; hospital; wastewater.

Abstract

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