Teicoplanin

S. aureus isolates were tested for in vitro susceptibility to ampicillin, amikacin, gentamicin, clindamycin, erythromycin, tetracycline, linezolid, teicoplanin, rifampicin, and quinupristin-dalfopristin (Mast Diagnostics Ltd, Merseyside, UK) by the disk diffusion method, based on the direction of the Clinical and Laboratory Standards Institute (CLSI) guide [12 ]. The minimum inhibitory concentration (MIC) for vancomycin and mupirocin was determined by the broth microdilution method in accordance with the CLSI recommendation. The MIC cutoff points for vancomycin based on the CLSI criteria were as follows: resistant, ≥ 16 μg/mL; intermediate, 4–8 μg/mL; and susceptible, ≤ 2 μg/mL. Strains were considered to demonstrate low-level mupirocin resistance (LLMUPR) if the MIC value was between 8–256 μg/mL, and high-level mupirocin resistance (HLMUPR) if the MIC value was ≥ 512 μg/mL. MDR isolates are defined by resistance to 3 or more unique antibiotic classes [1 (link),13 ]. ATCC29213 and ATCC25923 (S. aureus) were considered as the reference strains for quality control purposes. For MRSA screening, phenotypic growth was investigated around the cefoxitin disc (30 μg) placed on Mueller-Hinton agar plates (Merck, Germany), containing 4% NaCl. PCR was applied for genotypic amplification of mecA genes [12 ].