Distribution of Mupirocin Resistance in Nasal Carriers of Methicillin-resistant Staphylococcus aureus Among ICU Healthcare Workers and Patients in Rasht, Iran.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) represents a significant public health concern, contributing to infections in both community settings and clinical environments. Healthcare professionals, in particular, demonstrate elevated rates of MRSA colonization. This research focused on assessing the resistance to mupirocin prevalence among nasal MRSA carriers in intensive care unit (ICU) healthcare workers. MATERIALS & METHODS: Nasal swabs were obtained from hospitalized patients and healthcare staff, and S. aureus was identified through biochemical and microbiological tests. Antibiograms were conducted on isolated strains, employing a 30 μg cefoxitin disc for MRSA detection, while mupirocin resistance was identified using the disc-diffusion technique (Kirby-Bauer method). The minimum inhibitory concentration (MIC) for mupirocin, as well as the detection of the mupA and mupB genes, was accomplished by polymerase chain reaction (PCR). RESULTS: Of the 81 S. aureus isolates collected from nasal carriers, 20(24.69%) originated from ICU staff, while 61(75.31%) were from patients. MRSA constituted 77.7% (63/81) of the isolates overall. High-level resistance to mupirocin was detected in 34.56% (28/81) of isolates when tested with a 200 µg mupirocin disc, with the mupA gene detected in the same proportion of isolates. Notably, no low-level mupirocin resistance or mupB gene presence was identified in this study. Resistance rates to other antibiotics included rifampin (74.07%), penicillin (87.65%), amikacin (34.56%), gentamicin (56.79%), tetracycline (83.95%), erythromycin (100%), and clindamycin (100%). No resistance was observed for linezolid or Synercid. CONCLUSION: The study revealed higher mupirocin resistance among healthcare workers compared to patients, underscoring the need for regular screening of healthcare staff and comprehensive antibiotic resistance profiling to mitigate MRSA transmission within hospital settings.