Duarte, Ana S.

Figueiredo, Sofia

Henriques, Isabel

Manaia, Célia

Tacão, Marta

Tavares, Rafael D. S.

English

Repositório Institucional da Universidade Católica Portuguesa

CONGRESS OF MICROBIOLOGY AND BIOTECHNOLOGY 2019December 5th-7th, 2019University of Coimbra (Pólo II)BOOK OF ABSTRACTS67 I1. Environmental Microbiology and Biotechnology FP3. Characterization of multi-drug resistant Escherichia coli in the UV-treated outflow of an Urban Wastewater Treatment Plant Rafael D. S. Tavares1, Marta Tacão1, Sofia Figueiredo1, Ana S. Duarte2, Célia M. Manaia3, Isabel Henriques4 1Biology Department and CESAM, University of Aveiro, Aveiro, Portugal 2Instituto de Ciências da Saúde and CESAM, Universidade Católica Portuguesa, Viseu, Portugal 3Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina – Laboratório Associado, Escola Superior de Biotecnologia, Porto, Portugal 4Department of Life Sciences and CESAM, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal E-mail: rafael.tavares@ua.ptWastewater Treatment Plants are sources of antibiotic resistance into aquatic environments, contributing to the spread of clinically-relevant antibiotic-resistant bacteria. The disinfection (e.g. UV-C irradiation) of the final effluent is a promising strategy to circumvent this problem. However, some clinically-relevant resistant bacteria are known to survive disinfection. In this work we characterized Escherichia coli strains isolated from a UV-C-treated wastewater effluent, aiming to infer possible human health risks associated with these effluents. Multi-drug resistant (MDR) E. coli isolates (n=25) were genotyped (fingerprinting, Multi Locus Sequencing Typing and Clermont phylo-groups). Antibiotic resistance and virulence genes (ARGs and VG) were PCR-screened and plasmid transfer was assessed by mating assays. Cytotoxicity and invasion into mammalian cells were determined. The genome of 6 isolates was sequenced, and their survival in freshwater microcosms was evaluated. Genotyping distributed the strains into 3 groups, corresponding to phylogroups B2-sgI (n=7 isolates), A (n=16) and C (n=2). Based on MLST analyses phylogroup B2 strains were classified as ST131, C strains as ST410, and A as ST155 (n=4), ST58 (n=1), ST453 (n=2), ST617 (n=2), ST744 (n=1), ST1284 (n=3), or as a novel ST (n=3). Nine of the 18 PCR-screened ARGs were detected: sul1 (n=15 isolates), sul2 (n=15), tet(A) (n=14), blaOXA-1-like (n=8), tet(B) (n=8), aacA4-cr (n=5), aacA4 (n=2), sul3 (n=2) and qnrS1 (n=1). No VG were detected by PCR. Conjugal transfer of cefotaxime resistance was confirmed in 8/25 strains, in some cases yielding MDR phenotypes. Nine strains were significantly more cytotoxic than the positive control, and 10/21 strains were capable of internalization into Vero cells. Whole genome analysis evidenced the presence of additional ARGs (e.g. catB3, aadA2, strA, strB) and of VG encoding toxins, siderophores, and adhesion and invasion factors. After 28 days of incubation in freshwater microcosms, 4 strains were still detected by cultivation and/or qPCR. This study demonstrates that MDR E. coli can survive UV-wastewater disinfection, maintain resistance and gene transfer capacity and, eventually, persist in freshwater environments. These evidences support the hypothesis that even disinfected wastewater, if not adequately controlled, may represent a risk for human health.  Acknowledgements: FCT financing to CESAM (UID/AMB/50017) and through project STARE (WaterJPI/0001/2013).  

Characterization of multi-drug resistant Escherichia coli in the UV-treated outflow of an urban wastewater treatment plant

https://repositorio.ucp.pt/bitstream/10400.14/29645/1/FP3.%20Characterization%20of%20multi-drug%20resistant%20Escherichia%20coli%20in%20the%20UV-treated%20outflow%20of%20an%20Urban.pdf

Characterization of multi-drug resistant Escherichia coli in the UV-treated outflow of an urban wastewater treatment plant

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