Antimicrobial susceptibility was determined using the disc diffusion method, in accordance with the Clinical and Laboratory Standard Institute (CLSI) [27 (link)] for the following antibiotics: Ampicillin (AMP, 10 µg), cefoxitin (FOX, 30 µg), cefotaxime (CTX, 30 µg), ciprofloxacin (CIP, 5 µg), norfloxacin (NOR, 10 µg), tobramycin (TOB, 10 µg), gentamicin (GEN, 10 µg), doxycycline (DOX, 5 µg), amikacin (AMK, 30 µg), azithromycin (AZM, 15 µg), nitrofurantoin (NIT, 300 µg), amikacin, vancomycin (VA, 30 µg), linezolid (LZD, 30 µg) and sulfamethoxazole/trimethoprim (SXT, 1.25/23.75 µg) (Oxoid, Hampshire, England). The results were interpreted using the criteria outlined in CLSI guidelines based on the inhibition zone produced, which correlate with susceptibility levels [27 (link)]. The obtained results were used to identify the percentage of MDR among the tested isolates. As previously documented, multidrug resistance (MDR) is defined as resistance to three or more antimicrobial classes [28 (link)]. The phenotypic identification of the isolates as MRSA was performed against cefoxitin through the disk diffusion method, while the standard strain of S. aureus (ATCC 29312) was included as a control isolate.
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