Qin Yang,Yao Zhu,Stefan Schwarz,Lingli Wang,Wenyu Liu,Wenlin Yang,Siguo Liu,Wanjiang Zhang

Int J Antimicrob Agents.2023 Mar 16;106793.doi: 10.1016/j.ijantimicag.2023.106793. Online ahead of print.

Abstract

Mobile genetic elements (MGEs), such as integrative and conjugative elements (ICEs), plasmids and translocatable units (TUs), are main drivers for the spread of antibiotic resistance. Although ICEs have been reported to be capable of supporting the spread of plasmids among different bacteria, its role of mobilizing the resistance plasmids and TUs has not yet fully explored. In this study, a novel TU bearing optrA, a novel non-conjugative plasmid p5303-cfrD carrying cfr(D) and a new member of the ICESa2603 family, ICESg5301, were identified in streptococci. PCR assays revealed that three different types of cointegrates can be formed by IS1216E-mediated cointegration between the three different MGEs, including ICESg5301::p5303-cfrD::TU, ICESg5301::p5303-cfrD, and ICESg5301::TU. Conjugation assays showed that ICEs carrying p5303-cfrD and/or TU were able to successfully transfer into recipient strains, and thereby confirmed that ICEs can serve as vectors for other non-conjugative MGEs, such as TUs and p5303-cfrD. As neither the TU, nor plasmid p5303-cfrD can spread on their own between different bacteria, their integration into an ICE via IS1216E-mediated cointegrate formation not only increases the plasticity of ICEs, but also furthers the dissemination of plasmids and TUs carrying oxazolidinone resistance genes.

Keywords: IS1216E; Integrative and conjugative elements; Streptococci; plasmid; translocatable units.