Characterization of antimicrobial resistance in Salmonella enterica food and animal isolates from Colombia: identification of a qnrB19-mediated quinolone resistance marker in two novel serovars

Abstract

Ninety-three Salmonella isolates recovered from commercial foods and exotic animals in Colombia were studied. The serotypes, resistance profiles and where applicable the quinolone resistance genes were determined. Salmonella Anatum (n=14), Uganda (19), Braenderup (10) and Newport (10) were the most prevalent serovars, and resistance to tetracycline (18.3%), ampicillin (17.2%) and nalidixic acid (14%) was most common. Nalidixic acid-resistant isolates displayed minimum inhibitory concentrations ranging from 32 to 1024 μg mL(-1) . A Thr57→Ser substitution in ParC was the most frequent (12 of the 13 isolates). Six isolates possessed an Asp87→Tyr substitution in GyrA. No alterations in GyrA in a further seven nalidixic acid-resistant isolates were observed. Of these, four serovars including two Uganda, one Infantis and a serovar designated 6,7:d:-, all carried qnrB19 genes associated with 2.7 kb plasmids, two of which were completely sequenced. These exhibited 97% (serovar 6,7:d:- isolate) and 100% (serovar Infantis isolate) nucleotide sequence identity with previously identified ColE-like plasmids. This study demonstrates the occurrence of the qnrB19 gene associated with small ColE plasmids hitherto unrecognized in various Salmonella serovars in Colombia. We also report unusual high-level quinolone resistance in the absence of any DNA gyrase mutations in serovars S. Carrau, Muenchen and Uganda.

Small Plasmids Harboring qnrB19 : a Model for Plasmid Evolution Mediated by Site-Specific Recombination at oriT and Xer Sites

“…Plasmid pPAB19-1 is identical to a plasmid that has been isolated from E. coli, E. fergusonii, E. hermanii, Enterobacter aerogenes, K. pneumoniae, S. enterica, and Kluyvera ascorbata strains from the Netherlands, Bolivia, Peru, and Colombia by different research groups and has received several names (pSGI15, pECY6-7, and pMK100) (12,17,21,22). Plasmids pPAB19-2, pPAB19-3, and pPAB19-4 are highly related to pPAB19-1 and other plasmids such as pECC14-9 (Bolivia and Peru) and pMK101 (Colombia) isolated from E. coli and S. enterica, respectively (17,21,22). A ColE1-type replication region locus is within the fragment that is common to all plasmids and share 93% identity with other non-qnrB-carrying plasmids from enterobacteria such as pJHCMW1 (29).…”

“…The first qnrB gene (qnrB1) was identified in a plasmid from a K. pneumoniae strain isolated in South India (16), and 38 members of the family quickly followed (http://www.lahey .org/qnrStudies/) (13). The qnrB19 gene has been found in several genera of Enterobacteriaceae isolated from humans (healthy people and clinical isolates), animals, and food of animal origin in numerous geographical regions (6,9,12,17,21,22,27). An interesting characteristic of the qnrB19 allele is that it has been found within large plasmids, associated to ISEcp1C-based transposons (6,9,27), and in small plasmids (ϳ3 kbp) lacking ISEcp1C or any other insertion sequence (12,17,22) (Table 1).…”

Mechanisms of Fluoroquinolone Resistance in Escherichia coli Isolates from Food-Producing Animals

“…Preparation of bacterial DNA templates and PCR screening for plasmid-mediated determinants [including aac(6Ј)-Ib, qepA, qnrA, qnrB, and qnrS] were performed as described previously (16). QRDRs of the target DNA topoisomerase genes (gyrA, gyrB, parC, parE) were amplified using published PCR primers (1,20,30).…”

ShigellaAntimicrobial Drug Resistance Mechanisms, 2004–2014

“…Results were interpreted according to Clinical and Laboratory Standards Institute performance standards ( 6 ). All 344 isolates were screened for plasmid-mediated quinolone resistance (PMQR) genes ( 7 ). A subset of 34 isolates eliciting reduced susceptibility to nalidixic acid, ciprofloxacin, or both, and representing different years of isolation was subjected to PCR-based detection of mutations in the quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes ( 7 ).…”