Nasal Colonization and Molecular Characterization of Methicillin-Resistant Staphylococcus aureus among Hemodialysis Patients in 7 Korean Hospitals / 병원감염관리

ABSTRACT

BACKGROUND: Staphylococcus aureus is a major bacteremia-causing pathogen in hemodialysis patients, frequently colonizing patient skin and mucosa. Active infection control is necessary to prevent methicillin-resistant S. aureus (MRSA) infection in hospitals; however, the spread of community-associated MRSA has recently become a concern for MRSA infection control. We evaluated the nasal colonization of MRSA among hemodialysis patients and the molecular characterization of the MRSA isolates. METHODS: Nasal swabs were obtained from 482 hemodialysis patients in 7 nationwide hospitals in November 2009, and cultured for MRSA colonization. Swabs were inoculated and cultured in 6.5% NaCl tryptic soy broth, then subcultured on MRSASelect medium (Bio-Rad, Hercules, CA) for 20-24 h. Multiplex PCR was performed to analyze staphylococcal cassette chromosome mec (SCCmec) types of MRSA isolates. RESULTS: Of 482 hemodialysis patients, 57 (11.8%) carried MRSA, ranging from 6.7% to 19.0%. Among the 57 MRSA isolates, we identified 3 (5.3%) SCCmec II, 1 (1.8%) SCCmec IIA, 30 (52.6%) SCCmec IIB, 1 (1.8%) SCCmec III, 6 (10.5%) SCCmec IV, and 16 (28.1%) SCCmec IVA subtypes. CONCLUSION: The MRSA carriage rate (11.8%) of hemodialysis patients in this study was high. The SCCmec IIB subtype, a healthcare-associated strain, was the predominant strain, although SCCmec IV isolates, typically found in community-associated MRSA infections, were also frequently observed. To prevent healthcare-associated MRSA infections in hemodialysis patients, standardized infection control measures should be performed, and efforts to reduce MRSA carriage rates should be considered.