High prevalence and plasmidome diversity of -positive enterococci in a Shenzhen community, China.

BACKGROUND

The emergence of , which can confer resistance to phenicols and oxazolidinones in spp., poses a growing public health threat.

METHODS

102 -positive enterococci (OPEs) including various species were isolated from feces of 719 healthy volunteers in a Shenzhen community, China. Antimicrobial susceptibility of these isolates was tested. Whole-genome sequencing and bioinformatics analysis were performed to characterize molecular epidemiology of OPEs.

RESULTS

Compared to -negative enterococci (ONEs), antimicrobial resistance (linezolid, florfenicol, doxycycline, erythromycin and ciprofloxacin) and presence of antimicrobial resistance genes (ARGs) (, , (M), (A), (B) and etc) were higher in OPEs. Phylogenetic analysis revealed that high similarly (19-338 SNPs) was observed between the -positive from community and the strains from patients, animals, and environment. In 102 OPEs, the gene was detected on the chromosome ( = 36), on plasmids ( = 62), or both ( = 4). A diverse range of -carrying plasmid types was identified. The 9-plasmid replicons were widely detected in (44/66), whereas US1-plasmid replicons were widely identified in other enterococcal species (7/66). Most of all ARGs harbored by isolates were co-existed on -carrying plasmids, suggesting that the acquisition of -carrying plasmids will pose a greater threat to public health. Notably, the pAD1 (9 family) + DOp1-type plasmids should receive more attention for the transfer of given their high prevalence (36.36%), high number of co-located ARGs with (83.87% of total ARGs) and presence in multiple sources. Tn, IS, IS and IS are related to the transfer of chromosomal and plasmids-derived , respectively. The gene cluster, , and (A) were frequently identified surrounding and may be transferred with via IS or IS.

CONCLUSION

The transfer of gene is related to a variety of mobile elements (including plasmids, insertion sequences, transposons), which will promote the horizontal transfer of . Moreover, many ARGs co-exist with and could co-transfer with . The acquisition of OPEs and -carrying plasmids will pose a greater threat to public health and should be obtained more attention, especially -positive and pAD1 + DOp1-type plasmids.