Concentration dependent exposure of vancomycin and teicoplanin induces vanG regulon in Staphylococcus aureus

Therapeutic options for staphylococcus infections have been raised due to the emergence of VISA and VRSA. Six isolates of Staphylococcus aureus of clinical origin which were previously confirmed to carry vanG were selected for this study. Antimicrobial susceptibility was performed by disc diffusion method. Transcriptional expression of vanG and vanS_G showed down regulation against vancomycin and teicoplanin but expression was increased with increasing concentration of antibiotics. vanU_G, vanR_G showed up regulation against glycopeptide exposure. The present study underscored that expression of vanG and its regulatory gene operons are dependent on concentration of vancomycin and teicoplanin exposure in S.aureus.