AUTHOR=Li Xing-Yun , Yu Rui , Xu Chunyan , Shang Yanhong , Li Dexi , Du Xiang-Dang 

TITLE=A Small Multihost Plasmid Carrying erm(T) Identified in Enterococcus faecalis

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.850466

DOI=10.3389/fvets.2022.850466

ISSN=2297-1769

ABSTRACT=<p>The aim of this study was to determine the mobile genetic elements involved in the horizontal transfer of <italic>erm</italic>(T) in <italic>Enterococcus faecalis</italic>, and its transmission ability in heterologous hosts. A total of 159 erythromycin-resistant enterococci isolates were screened for the presence of macrolide resistance genes by PCR. Whole genome sequencing for <italic>erm</italic>(T)-carrying <italic>E. faecalis</italic> E165 was performed. The transmission ability in heterologous hosts was explored by conjugation, transformation, and fitness cost. The <italic>erm</italic>(T) gene was detected only in an <italic>E. faecalis</italic> isolate E165 (1/159), which was located on a 4,244-bp small plasmid, designed pE165. Using <italic>E. faecalis</italic> OG1RF as the recipient strain, pE165 is transferable. Natural transformation experiments using <italic>Streptococcus suis</italic> P1/7 and <italic>Streptococcus mutans</italic> UA159 as the recipients indicated it is transmissible, which was also observed by electrotransformation using <italic>Staphylococcus aureus</italic> RN4220 as a recipient. The <italic>erm</italic>(T)-carrying pE165 can replicate in the heterologous host including <italic>E. faecalis</italic> OG1RF, <italic>S. suis</italic> P1/7, <italic>S. mutans</italic> UA159, and <italic>S. aureus</italic> RN4220 and conferred resistance to erythromycin and clindamycin to all hosts. Although there is no disadvantage of pE165 in the recipient strains in growth curve experiments, all the pE165-carrying recipients had a fitness cost compared to the corresponding original recipients in growth competition experiments. In brief, an <italic>erm</italic>(T)-carrying plasmid was for the first time described in <italic>E. faecalis</italic> and as transmissible to heterologous hosts.</p>