Prevalence of plasmid-mediated multidrug resistance determinants in fluoroquinolone-resistant bacteria isolated from sewage and surface water

Abstract

Fluoroquinolones (FQs) are fully synthetic broad-spectrum antibacterial agents that are becoming increasingly popular in the treatment of clinical and veterinary infections. Being excreted during treatment, mostly as active compounds, their biological action is not limited to the therapeutic site, but it is moved further as resistance selection pressure into the environment. Water environment is an ideal medium for the aggregation and dissemination of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs), which can pose a serious threat to human health. Because of this, the aim of this study was to determine the number of fluoroquinolone-resistant bacteria (FQRB) and their share in total heterotrophic plate counts (HPC) in treated wastewater (TWW), and upstream and downstream river water (URW, DRW) samples where TWW is discharged. The spread of plasmid-mediated quinolone resistance (PMQR) determinants and the presence/absence of resistance genes to other most popular antibiotic groups (against tetracyclines and beta-lactams) in selected 116 multiresistant isolates were investigated. The share of FQRB in total HPC in all samples was rather small and ranged from 0.7 % in URW samples to 7.5 % in TWW. Bacteria from Escherichia (25.0 %), Acinetobacter (25.0 %), and Aeromonas (6.9 %) genera were predominant in the FQRB group. Fluoroquinolone resistance was mostly caused by the presence of the gene aac(6′)-1b-cr (91.4 %). More rarely reported was the occurrence of qnrS, qnrD, as well as oqxA, but qnrA, qnrB, qepA, and oqxB were extremely rarely or never noted in FQRB. The most prevalent bacterial genes connected with beta-lactams’ resistance in FQRB were blaTEM, blaOXA, and blaCTX-M. The blaSHV was less common in the community of FQRB. The occurrence of bla genes was reported in almost 29.3 % of FQRB. The most abundant tet genes in FQRB were tet(A), tet(L), tet(K), and tet(S). The prevalence of tet genes was observed in 41.4 % of FQRB. The highest prevalence of multidrug-resistant (MDR) microorganisms was detected in TWW and DRW samples. It indicates that discharged TWW harbors multiresistant bacterial strains and that mobile PMQR and ARGs elements may have a selective pressure for species affiliated to bacteria in the river water.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-016-6221-4) contains supplementary material, which is available to authorized users.

Application of NGS for studying the antibiotic resistant microbiome in Wrocław tap water

“…The drug concentrations were established in accordance to EUCAST, CLSI or the literature guidelines [8]. To determine the biodiversity of bacteria which can form biofilm in tap water, additional 1 L samples of cold (C-W) and hot water (H-W) were processed as mentioned above and the membranes were placed in conical flasks containing 30 ml of bullion (BTL) without antibiotic supplementation.…”

“…PCR mixtures consisted of ddH2O and 2xMasterMix (A&A Biotechnology), specific primers of concentrations ranging from 10 μM to 100 μM and 2 μl of plasmid DNA. 10 ARGs were investigated in this study, as presented in Table 1 (for primers sequences and PCR conditions, please see [8]). …”

“…All PCR products were determined by gel electrophoresis (15 min at 130 V and then 60 min at 80 V or 90 min at 80 V) in 1% (w/v) agarose gel (Merck) in 1xTBE buffer and visualized with ethidium bromide staining [8].…”

“…In addition, although the biodiversity (in terms of the most prevalent genera) of samples FQ and H-W are similar, the other ARGs were detected in their plasmid DNA. All of the tested ARGs are plasmid encoded [8].…”

Monitoring of drug resistance amplification and attenuation with the use of tetracycline-resistant bacteria during wastewater treatment

“…The use of activated sludge and biological membrane systems in the treatment process contributes to the exchange of genetic information between bacteria of the same or different species, including microorganisms from unrelated families [9]. The above facilitates the exchange of genes located on mobile plasmids, including those encoding drug resistance [10].…”