Mupirocin

Antimicrobial susceptibility assay was performed on all staphylococci according to the Clinical and Laboratory Standards Institute guidelines [44 ]. Sixteen antimicrobial agents were utilized for disc diffusion assays on Mueller–Hinton agar (MHA, Difco Laboratories): ampicillin (AMP, 10 μg), cefoxitin (FOX, 30 μg), penicillin (PEN, 10 μg), chloramphenicol (CHL, 30 μg), ciprofloxacin (CIP, 5 μg), enrofloxacin (ENR, 5 μg), levofloxacin (LEV, 5 μg), clindamycin (CLI, 2 μg), erythromycin (ERY, 15 μg), gentamicin (GEN, 10 μg), mupirocin (MUP, 200 μg), rifampicin (RIF, 5 μg), sulfamethoxazole-trimethoprim (SXT, 23.75/1.25 μg), quinupristin-dalfopristin (SYN, 15 μg), and tetracycline (TET, 30 μg). mupirocin was purchased from Oxoid (Hampshire, UK), and the rest of the antimicrobial agents were purchased from BD BBL^TM (Becton Dickinson, Franklin Lakes, NJ). The minimum inhibitory concentrations (MICs) of oxacillin (OXA), TET, CIP, and ENR were determined for all the study strains by using the standard two-fold broth microdilution [44 ]. The MICs of the study strains to vancomycin (VAN) and linezolid (LZD) were determined by standard Etest (AB Biodisk, Dalvagen, Sweden). S. aureus MW2 and S. aureus ATCC 29213 strains were used as reference strains for the antimicrobial susceptibility tests. All antimicrobial susceptibility tests were repeated three times.

The disc diffusion method was performed on Mueller-Hinton agar plates (bioMerieux) with following antibiotic paper discs - disc content (μg): cefoxitin (30 μg), erythromycin (15 μg), clindamycin (2 μg), mupirocin (10 μg), gentamicin (10 μg), amikacin (10 μg), tetracycline (30 μg), chloramphenicol (30 μg), trimethoprim/sulfamethoxazole (cotrimoxazole) (1.25/23.75 μg), (Becton Dickinson, USA). Tests were performed and interpreted according to the guidelines of the European Committee of Antimicrobial Susceptibility Testing (EUCAST) [16 ].