Dissemination of methicillin-resistant Staphylococcus aureus sequence type 45 among nursing home residents and staff in Taiwan

Unlike hospitals or the community, nursing homes provide a unique healthcare environment for patients. There have been no reports regarding methicillin-resistant Staphylococcus aureus (MRSA) carriage among nursing home residents and staff in Taiwan. From May to November 2012, a total of 523 subjects, including 360 residents and 163 staff, in 14 nursing homes in Taiwan were surveyed for nasal MRSA carriage. Overall, the nasal MRSA carriage rate was 20.1%, with 20.3% for residents and 19.6% for staff. For residents, age >60 years (adjusted OR 2.268; 95% CI 1.185–4.342; p 0.013) and the presence of chronic wounds (adjusted OR 2.449; 95% CI 1.082–5.544; p 0.032) were the significant risk factors for MRSA carriage in multivariate models. Among the 105 MRSA isolates, 11 pulsed-field gel electrophoresis (PFGE) patterns were identified, except for five isolates untypeable by SmaI digestion, with one major pattern; nine isolates (8.6%) possessed staphylococcal cassette chromosome (SCCmec) type II or III, 66 isolates type IV or V, and 21 isolates unidentified types. The clone characterized as PFGE pattern BM sequence type 45 was the most common clone, accounting for 50% of the isolates, and was multiresistant, including to ciprofloxacin. Intra-institutional and inter-institutional transmission of MRSA was documented by molecular methods. It was shown conclusively that one-fifth of residents and staff in nursing homes in Taiwan harboured MRSA, mostly ST45 strains, in their nares. Intra-institutional and inter-institutional transmission of MRSA was documented.