Nasal Carriage of Methicillin-Resistant Staphylococcus Aureus among Medical Students of Belgrade University

Introduction Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) present the growing problem in the whole world. Carriage of MRSA is most frequent in the nose, and medical students come in contact both with patients and different persons in the community. Therefore, they may be significant for the transmission of MRSA from hospitals to out-of-hospital communities and vice versa. Objective The aim of this study was to establish the carriage rate among students of the second, third and fourth year of study at the School of Medicine in Belgrade and to analyze their genotypic and phenotypic characteristics. Methods In total 533 nasal samples were taken. The samples were incubated in Trypcase-soy broth supplemented with 6.5% NaCl, and thereafter the swabs were inoculated on mannitol salt agar supplemented with 2 mu g/mL of oxacillin. The presence of nuc, mecA and Panton-Valentine leukocidin genes was examined by PCR.The characteristics of the MRSA strains were determined using: antibiotic susceptibility testing by Vitek2 System, SCCmec, agr typing and MLST. Results MRSA was isolated from two of 533 investigated samples (0.37%). MRSA were isolated from the students of the second and third year of study. Profiles of strains were: ST80 (SCCmec type IV, agr type 3) and ST152 (SCCmec type V, agr type 1). MRSA strains were multiresistant. Conclusion The nasal carriage rate of MRSA in population of medical students of the first year of study in Belgrade is low. Genotypic and phenotypic characteristics of MRSA strains indicate their community origin. MLST typing revealed that isolates belong to ST80 and ST152.