The prevalence and characterization of antibiotic-resistant and virulent Escherichia coli strains in the municipal wastewater system and their environmental fate

Adriana Osińska; Ewa Korzeniewska; Monika Harnisz; Sebastian Niestępski

doi:10.1016/j.scitotenv.2016.10.203

The prevalence and characterization of antibiotic-resistant and virulent Escherichia coli strains in the municipal wastewater system and their environmental fate

Sci Total Environ. 2017 Jan 15:577:367-375. doi: 10.1016/j.scitotenv.2016.10.203. Epub 2016 Nov 3.

Authors

Adriana Osińska¹, Ewa Korzeniewska², Monika Harnisz³, Sebastian Niestępski⁴

Affiliations

¹ Department of Environmental Microbiology, Faculty of Environmental Sciences, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1 Str., 10-720 Olsztyn, Poland. Electronic address: adriana.osinska@uwm.edu.pl.
² Department of Environmental Microbiology, Faculty of Environmental Sciences, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1 Str., 10-720 Olsztyn, Poland. Electronic address: ewa.korzeniewska@uwm.edu.pl.
³ Department of Environmental Microbiology, Faculty of Environmental Sciences, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1 Str., 10-720 Olsztyn, Poland. Electronic address: monika.harnisz@uwm.edu.pl.
⁴ Department of Environmental Microbiology, Faculty of Environmental Sciences, University of Warmia and Mazury in Olsztyn, Prawocheńskiego 1 Str., 10-720 Olsztyn, Poland. Electronic address: niestepski.sebastian@gmail.com.

PMID: 27816226
DOI: 10.1016/j.scitotenv.2016.10.203

Abstract

Antibiotics are widely used in human and veterinary medicine and in animal production, which increases their concentrations in aquatic ecosystems and contributes to selective pressure on environmental microorganisms. The objective of this study was to identify antibiotic resistance determinants in Escherichia coli strains isolated from untreated and treated wastewater (UWW and TWW) and from river water sampled downstream and upstream (URW and DRW) from the effluent discharge point. The analyzed antibiotic groups were beta-lactams, tetracyclines and fluoroquinolones which are widely used in human and veterinary medicine. The virulence of the isolated E. coli strains was also analyzed, and their clonal relatedness was determined by ERIC (enterobacterial repetitive intergenic consensus sequence) PCR. The highest counts of bacteria resistant to beta-lactams, tetracyclines and fluoroquinolones were noted in UWW at 6.4×10⁴, 4.2×10⁴ and 3.1×10³CFU/mL, respectively. A total of 317 E. coli isolates resistant to at least one group of antibiotics were selected among bacterial isolates from river water and wastewater samples. Nearly 38% of those isolates were resistant to all of the tested antibiotics. The highest percent (43%) of multidrug-resistant isolates was noted in UWW samples. Isolates resistant to beta-lactams most frequently harbored bla_TEM and bla_OXA genes. The group of genes encoding resistance to tetracyclines was most frequently represented by tetA, tetB and tetK, whereas the qnrS gene was noted in isolates resistant to fluoroquinolones. Virulence genes bfpA (65%), ST (56%) and eae (39%) were most widely distributed in all isolates, regardless of their origin. The results of this experiment reveal the dangers associated with environmental contamination by drug-resistant and virulent E. coli strains distributed with treated wastewater. Multidrug resistance was determined more frequently in strains isolated from DRW than in isolates from URW samples. Our findings provide valuable inputs for evaluating public health hazards associated with bacterial contamination.

Keywords: Antibiotics; Escherichia coli; Multidrug resistance; Surface water; Virulence; Wastewater.

MeSH terms

Anti-Bacterial Agents
Drug Resistance, Multiple, Bacterial*
Escherichia coli / drug effects
Escherichia coli / isolation & purification*
Microbial Sensitivity Tests
Poland
Wastewater / microbiology*

Substances

Anti-Bacterial Agents
Waste Water