Plasmid-mediated quinolone resistance (PMQR) and mutations in the topoisomerase genes of Salmonella enterica strains from Brazil

Abstract

The objective of this study was to identify mutations in the Quinolone Resistance Determining sources Regions (QRDR) of the gyrA, gyrB, parC, and parE genes and to determine if any of the qnr variants or the aac(6′)-Ib-cr variant were present in strains of Salmonella spp. isolated in Brazil. A total of 126 Salmonella spp. strains from epidemic (n = 114) and poultry (n = 12) origin were evaluated. One hundred and twelve strains (88.8%) were resistant to nalidixic acid (NAL) and 29 (23.01%) showed a reduced susceptibility to ciprofloxacin (Cip). The mutations identified were substitutions limited to the QRDR of the gyrA gene in the codons for Serine 83, Aspartate 87 and Alanine 131. The sensitivity to NAL seems to be a good phenotypic indication of distinguishing mutated and non-mutated strains in the QRDR, however the double mutation in gyrA did not cause resistance to ciprofloxacin. The qnrA1 and qnrB19 genes were detected, respectively, in one epidemic strain of S. Enteritidis and one strain of S. Corvallis of poultry origin. Despite previous detection of qnr genes in Brazil, this is the first report of qnr gene detection in Salmonella, and also the first detection of qnrB19 gene in this country. The results alert for the continuous monitoring of quinolone resistance determinants in order to minimize the emergence and selection of Salmonella spp. strains showing reduced susceptibility or resistance to quinolones.

High prevalence and molecular characteristics of multidrug-resistant Salmonella in pigs, pork and humans in Thailand and Laos provinces

“…Many PMQR isolates in this study exhibited low nalidixic and ciprofloxacin resistance levels (as low as 8.0 and 0.03 µg ml À1 , respectively). This finding contradicts previous studies suggesting that the presence of qnr genes mediates reduced susceptibility to ciprofloxacin and nalidixic acid (Hopkins et al, 2008;Ferrari et al, 2013). The data suggest that PMQR-carrying isolates could be missed if resistance to nalidixic acid and ciprofloxacin are the exclusion criteria used to select isolates for further genetic screening.…”

Salmonellosis detection and evidence of antibiotic resistance in an urban raccoon population in a highly populated area, Costa Rica

“…Nevertheless, plasmid‐mediated quinolone resistance in Salmonella is an alternative resistance mechanism that employs an enzyme to shield DNA gyrase and type IV topoisomerase from quinolone inhibition (Al‐Gallas et al, ; van Hoek et al, ). The horizontal transmission of qnr genes increases resistance to quinolones such as ciprofloxacin, which could explain why one serovar was only resistant to ciprofloxacin but not to nalidixic acid (Aldred et al, ; Ata, Yibar, Arslan, Mustak, & Gunaydin, ; Cavaco & Aarestrup, ; Ferrari et al, ; Pribul et al, ).…”

“…The horizontal transmission of qnr genes increases resistance to quinolones such as ciprofloxacin, which could explain why one serovar was only resistant to ciprofloxacin but not to nalidixic acid (Aldred et al, 2014;Ata, Yibar, Arslan, Mustak, & Gunaydin, 2014;Cavaco & Aarestrup, 2009;Ferrari et al, 2013;Pribul et al, 2016).…”

Quinolone susceptibility and genetic characterization of Salmonella enterica subsp. enterica isolated from pet turtles

“…In addition to above two sites, a recent study reported gyrA mutations of Ala-131 position in poultry and human isolates [30]. Another study could detect mutations in parC in addition to the gyrA mutations but in very low rate compared to gyrA [36].…”