Analysis of Two Pheromone-responsive Conjugative Multiresistance Plasmids Carrying the Novel Mobile Locus from

The acquired gene, which encodes a ribosomal protection protein of the ABC-F family, can confer cross-resistance to linezolid and florfenicol, posing a serious therapeutic challenge to both human and veterinary medicine. The objective of this study was to investigate the two () plasmids for their fine structure, their transferability and the presence of mobile antimicrobial resistance loci. To elucidate their fine structure, the two plasmids were completely sequenced and the sequences analysed. Besides conjugation experiments, inverse PCR assays were conducted to see whether minicircles are produced from the mobile antimicrobial resistance loci. Two pheromone-responsive conjugative -carrying plasmids from , pE211 and pE508 were identified, which can transfer with frequencies of 2.6 ×10 and 3.7 ×10 (transconjugant per donor), respectively. In both plasmids, was located on the novel mobile locus with different sizes (12,834 bp in pE211 and 7,561 bp in pE508, respectively), flanked by two copies of IS genes in the same orientation. Inverse PCR revealed that circular forms can be generated, consisting of and one copy of IS1216, indicating they are all active. The 77,562 bp plasmid pE211 also carried Tn and a mobile ABDR locus, and the 84,468 bp plasmid pE508 also harbored the genes , (L), (O/W/32/O) and a mobile (A)-(D) locus. The presence of mobile genetic elements in these plasmids renders them flexible and these elements will aid to the persistence and dissemination of these plasmids among enterococci and potentially also other gram-positive bacteria.