Characterization and comparative genomics analysis of RepA_N multi-resistance plasmids carrying from .

INTRODUCTION

This research aimed to investigate the antibiotic resistance of from swine farms in Zhejiang Province and the prevalence and transmission mechanism of oxazolidone resistance gene .

METHOD

A total of 226 were isolated and their resistance to 14 antibiotics was detected by broth microdilution. The resistance genes were detected by PCR.

RESULTS

The antibiotic resistance rate of 226 isolates to nearly 57% (8/14) of commonly used antibiotics was higher than 50%. The resistance rate of tiamulin was highest (98.23%), that of tilmicosin, erythromycin, tetracycline and florfenicol was higher than 80%, and that of oxazolidone antibiotic linezolid was 38.49%. The overall antibiotics resistance in Hangzhou, Quzhou and Jinhua was more serious than that in the coastal cities of Ningbo and Wenzhou. The result of PCR showed that was the main oxazolidinone and phenicols resistance gene, with a detection rate of 71.68%, and often coexisted with in the isolates. Through multi-locus sequence typing, conjugation transfer, and replicon typing experiments, it was found that the horizontal transmission mediated by RepA_N plasmid was the main mechanism of resistance gene transmission in E. faecalis from Zhejiang Province. Two conjugative multi-resistance plasmids carrying , RepA_N plasmid pHZ318- from Hangzhou and Rep3 plasmid from Ningbo, were sequenced and analyzed. pHZ318- contain two multidrug resistance regions (MDR), which contributed to the MDR profile of the strains. and resistance genes coexisted in ISE----(A)-ISE complex transposon, and there was a partial sequence of Tn transposon downstream. However, pNB304-optrA only contain , and an insertion sequence IS. The presence of mobile genetic elements at the boundaries can possibly facilitate transfer among through inter-replicon gene transfer.

DISCUSSION

This study can provide theoretical basis for ensuring the quality and safety of food of animal origin, and provide scientific guidance for slowing down the development of multi-antibiotic resistant .