First detection of multiresistance pRE25-like elements from Enterococcus spp. in Staphylococcus pseudintermedius isolated from canine pyoderma.

OBJECTIVES: Enterococcus pRE25 is a conjugative and mobilising multiresistance plasmid from Enterococcus faecalis RE25. pRE25-like enterococcal plasmid pWZ909 mediates the delivery of vancomycin resistance to methicillin-resistant Staphylococcus aureus via a Tn1546-like transposon. However, whether pRE25-like elements contribute to multidrug resistance in Staphylococcus spp. has not yet been investigated. Here we describe the first detection of multiresistance pRE25-like elements in the chromosomal DNA of multidrug-resistant Staphylococcus pseudintermedius (MDRSP).

METHODS: A total of 46 MDRSP clinical strains were isolated from canine pyoderma in Korea. Their genetic characteristics were analysed by multilocus sequence typing (MLST) and PCR targeting pRE25-like elements. Whole-genome sequencing (WGS) was performed on four isolates.

RESULTS: WGS detected that the chromosomal 22-kb pRE25-like elements contained five antimicrobial resistance genes [cat, erm(B), aphA-3, aadK and sat4], IS1252, IS256, and a toxin-antitoxin system within copies of IS1216. BLASTn alignment analysis revealed that 84% of the chromosomal 22-kb pRE25-like elements sequence is homologous (99.8% identity) to the enterococcal pRE25 plasmid sequence. PCR assay showed that 52.2% of MDRSP isolates were positive for pRE25-like elements and were presumed to contain pRE25-like elements (pRE25 group). The sequence types (STs) of the pRE25 group were diverse, with 18 STs identified, among which 12 STs were first reported in Korea.

CONCLUSION: Enterococcal pRE25-like elements are suspected to be widespread in MDRSP isolated from companion dogs in Korea. Considering that companion dogs live in a closely shared environment with humans, continuous surveillance of pRE25-like elements is needed for other staphylococci commonly isolated from humans.