Caracterização genética de plasmídeos relacionados com a resistência a quinolonas em Escherichia coli

Abstract

Wastewater and some surface water bodies represent important reservoirs of resistant bacteria and of antibiotic resistance genes, for example of the genus Escherichia, mainly in urban environments. In recent years, beta-lactam- and quinolone-resistant E. coli has been increasing due to horizontal gene transfer and several genes associated with these resistance types are known to be located in plasmids, in particular in plasmids belonging to incompatibility group F (incF). In this study, 11 ciprofloxacin-resistant Escherichia spp. isolates were characterized in order to get additional insights about the modes of dispersion of quinolone resistance. The strains studied, nine E. coli and two E. fergusonii, were isolated from municipal and hospital wastewater. The screening of resistance genetic determinants to quinolones, beta-lactams and integrons revealed the presence of the genes aac(6’)-Ib-cr (n=4), qepA (n=2) and qnrS (n=1), blaTEM (n=6), blaOXA (n=3), ampC (n=11) and class 1 integrons (n=10). Other resistance genetic determinants such as qnrA, qnrB, qnrC, qnrD, blaCTX and blaSHV, also screened in this study, were not found. Incompatibility group characterization allowed not only the detection of incF plasmids in all isolates, but also incI1 (n=2), incN (n=2), incY (n=2), IncA/C (n=2), incK (n=2) and incB/O (n=3), After transformation assays, using reference strain E. coli Top10 as recipient, incF plasmids were acquired from two donor strains, as well as genes aac(6’)-Ib-cr (1/2), qnrS (1/2), blaTEM (1/2) and ampC (2/2). Multilocus Sequence Typing (MLST) of incF replicons revealed seven distinct genotypes. This work suggests high plasmid diversity among Escherichia spp. strains from municipal or hospital wastewater and that they may be linked to quinolone and beta-lactam resistance dissemination. Future studies will help perceive which environmental factors can enhance the transfer of these plasmids to other bacteria.

Date of Award	2014
Original language	Portuguese
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Célia Manaia (Supervisor)