摘要
This study aimed to compare the ability of linezolid and vancomycin to prevent the clinical methicillin-resistant Staphylococcus aureus(MRSA)resistant mutant by determining mutant prevention concentration(MPC).We further investigated the possible molecular mechanism associated with reduced vancomycin susceptibility in the mutant strains by molecular fingerprinting techniques.Fifty-six clinical MRSA isolates were enriched in broth,and the bacterial concentration was adjusted to 1010 CFU/mL for MPC determination.Wild-type strains and mutant strains selected by vancomycin during MPC determination were characterized by pulsed-field gel electrophoresis(PFGE),Sau-PCR assay,denaturing gradient gel electrophoresis(DGGE),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Our results showed that both linezolid and vancomycin might have great ability to restrict the selection of resistant mutants of MRSA.Linezolid had a narrower mutant selection window against the MRSA isolates than vancomycin.Sau-PCR assay and PFGE revealed that pre-scanning and post-scanning strains selected by vancomycin during the experimental process of MPC had different DNA profiles.TEM and SEM showed that the mutant strains had slightly thicker cell walls than the wild-type strains.DDGE was used to probe for mutations in the graS gene,but no different banding patterns were observed on the electrophoretogram spectrum.Linezolid showed greater ability to restrict the selection of resistant mutants of MRSA than vancomycin.In wild-type strains and mutant strains selected by vancomycin during the experimental process of MPC,there may be mutations in genes other than the graS gene or existence of other resistant mechanisms.
This study aimed to compare the ability of linezolid and vancomycin to prevent the clinical methicillin-resistant Staphylococcus aureus(MRSA)resistant mutant by determining mutant prevention concentration(MPC).We further investigated the possible molecular mechanism associated with reduced vancomycin susceptibility in the mutant strains by molecular fingerprinting techniques.Fifty-six clinical MRSA isolates were enriched in broth,and the bacterial concentration was adjusted to 1010 CFU/mL for MPC determination.Wild-type strains and mutant strains selected by vancomycin during MPC determination were characterized by pulsed-field gel electrophoresis(PFGE),Sau-PCR assay,denaturing gradient gel electrophoresis(DGGE),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Our results showed that both linezolid and vancomycin might have great ability to restrict the selection of resistant mutants of MRSA.Linezolid had a narrower mutant selection window against the MRSA isolates than vancomycin.Sau-PCR assay and PFGE revealed that pre-scanning and post-scanning strains selected by vancomycin during the experimental process of MPC had different DNA profiles.TEM and SEM showed that the mutant strains had slightly thicker cell walls than the wild-type strains.DDGE was used to probe for mutations in the graS gene,but no different banding patterns were observed on the electrophoretogram spectrum.Linezolid showed greater ability to restrict the selection of resistant mutants of MRSA than vancomycin.In wild-type strains and mutant strains selected by vancomycin during the experimental process of MPC,there may be mutations in genes other than the graS gene or existence of other resistant mechanisms.
引文