ABSTRACT
Objective To investigate the mechanism of linezolid resistance in methicillin-resistant Staphylococcus epidermidis ( MRSE) strains isolated in Hangzhou area. Methods Twenty-three linezolid-re-sistant Staphylococcus epidermidis ( LRSE) strains were isolated from the patients with septicaemia, urinary tract infection or infectious pleuritis in several hospitals in Hangzhou area during May, 2013 to April, 2015. The minimal inhibition concentrations ( MICs) of thirteen different antibiotics against the LRSE strains were detected by using E-test. Pulsed-field gel electrophoresis ( PFGE) and cluster analysis were performed for homology analysis. Correlations between linezolid resistance in the LRSE strains and G2576T mutation at theⅤ functional region of 23S rRNA gene or cfr gene were determined by PCR and sequencing analysis. Re-sults The MICs of linezolid to 15 LRSE strains were higher than 256 μg/ml while to the other 8 LRSE strains were 6 or 8 μg/ml. All of the 23 LRSE strains were resistant to both oxacillin and cefoxitin. Among the LRSE strains with high linezolid MICs (MIC>256 μg/ml), LRSE1 and LRSE2, LRSE3-LRSE6 and LRSE9-LRSE12 respectively belonged to the same clone line and came from the same hospital. All of the 23 LRSE strains carried the cfr gene. Moreover, the G2576T mutation at theⅤfunctional region of 23S rRNA gene was detected in the 15 LRSE strains with high linezolid MICs ( MIC>256 μg/ml ) , but not in the 8 strains with lower linezolid MICs ( MIC=6 or 8 μg/ml) . Conclusion There are significant differences in linezolid resistance among LRSE strains isolated in Hangzhou area. The LRSE strains are methicillin-resist-ant coagulase negative Staphylococcus ( MRCNS) strains and widely distributed. The linezolid resistance in LRSE strains is related to the G2576T mutation at theⅤfunctional region of 23S rRNA gene and cfr gene.