抄録
Dissemination of multidrug-resistant Staphylococcus epidermidis, especially methicillin-resistant S. epidermidis (MRSE), with enhanced pathogenicity is a serious global public health concern. We characterized the antimicrobial/biocide susceptibility and virulence of 105 S. epidermidis bloodstream isolates from two hospitals in Tokyo to expand on the limited information available in Japan.
The phenotypic and genetic features of antimicrobial resistance, biocide tolerance, SCCmec type, and biofilm development or adhesion were analyzed.
In total, 76 (72.4%) isolates were identified as MRSE, which showed higher resistance rates to most antimicrobial classes, except for vancomycin, than methicillin-susceptible S. epidermidis (MSSE). MRSE was classified into 16 sequence types (STs), including the most prevalent ST2, which is a global high-risk S. epidermidis clone. In addition, our MRSE isolates possessed higher rates of qacA/B than the MSSE isolates, resulting in a higher tolerance to the three low-level antiseptics compared to MSSE isolates. Among these, ST6 and ST2 isolates showed higher qacA/B positivity rates. Furthermore, SCCmec type IV was predominant in the MRSE isolates. MRSE isolates possessed aap and IS256 more frequently than MSSE isolates. Moreover, sesI and icaA were found in the ST2 isolates. The proportion of biofilm producers in MRSE tended to be higher than that in MSSE, and strong biofilm producers were concentrated in ST2 isolates among the four predominant STs.
Collectively, our findings provide the first evidence that highly virulent, multidrug-resistant S. epidermidis isolates, including the global ST2 MRSE lineage, may have already spread and persisted for a long time in healthcare facilities in Japan.
