Dissemination of IncFII plasmids carrying rmtB and qepA in Escherichia coli from pigs, farm workers and the environment

Abstract

Fifty-one fluoroquinolone-resistant Escherichia coli isolates recovered from pigs, workers and environmental samples in one pig farm were screened for 16S rRNA methylase genes and qepA, a fluoroquinolone efflux pump gene, by PCR. Clonal relatedness of the E. coli isolates was examined by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing and phylogenetic analysis. Plasmids from the E. coli isolates were characterized by incompatibility group, restriction enzyme digestion and Southern hybridization analysis. The genetic environment of rmtB and qepA was also determined by PCR mapping. Eleven isolates that were highly resistant to amikacin and fluoroquinolones were positive for rmtB and qepA. All of these isolates belonged to phylogenetic group A, but most of them had different PFGE patterns or belonged to different sequence types (STs). Four isolates from different sources (two from pigs, one from a farm worker and one from an environmental sample) belonged to the same ST (ST160). Both rmtB and qepA were located on approximately 75-kb IncFII conjugative plasmids with nearly the same EcoRI digestion pattern. Tn3, IS26 and ISCR3 were found to be associated with rmtB and qepA. This study has found, for the first time, the transmission of rmtB and qepA among E. coli isolates from pigs, farm workers and the environment. Both horizontal transfer of IncFII plasmids and clonal dissemination have occurred and been seen to contribute to the dissemination of these resistance genes in a pig farm.

Comparison of antimicrobial resistance phenotypes and genotypes in enterotoxigenic Escherichia coli isolated from Australian and Vietnamese pigs

“…The commercial Vietnamese piggery collection had a higher level of resistance and a higher frequency of ARGs for almost all drug classes compared with the village piggeries, suggesting that commercial animals had more exposure to a greater array of at the smallholder farmer's discretion [14] and reports state that fluoroquinolones may be overprescribed or misused both in human and veterinary medicine [22,23]. The high frequency of qnrB in susceptible isolates may indicate that antimicrobial selective pressure is promoting dissemination of transferable plasmid-mediated resistance determinants, which may reduce susceptibility to fluoroquinolones and facilitate the development of stepwise point mutations in chromosomal target genes [24].…”

Incidence of Shiga toxin–producing Escherichia coli strains in beef, pork, chicken, deer, boar, bison, and rabbit retail meat

“…Consequently, they are likely to be subject to horizontal gene transfer between the species as exhibited by dissemination of plasmids in E. coli between pigs, farm workers, and the environment. 10 It has been challenging to determine the prevalence of the STEC O-groups in food, as there are only a few methods known for confirming the O-groups. The traditional method for detecting the O-groups is serotyping, which is laborintensive and may provide equivocal results.…”

Molecular Characterization of bla NDM-5 Carried on an IncFII Plasmid in an Escherichia coli Isolate from a Nontraveler Patient in Spain

“…NDM enzymes encoded in IncFII plasmids, with a narrow host range, are being increasingly reported (12)(13)(14)(15)(16)(17), an observation that deserves further attention since IncFII plasmid scaffolds have been linked to the worldwide spread of CTX-M-15 (18). Of note, the genetic array bla TEM-1 -rmtB-IS26 upstream from bla NDM in both pHC105-NDM and pMC-NDM has also typically been associated with the Tn3 transposon in IncFII plasmids (19)(20)(21)(22), and it is not unlikely that linkage of this array with the NDM module originated from an IS26-mediated recombination event, a common mechanism in the mobilization and genetic rearrangement of NDM-related structures (13,14).…”