Prevalence, Prediction, and Clonality of Methicillin-Resistant Staphylococcus aureus Carriage at Admission to Medical Units in Hong Kong, China

Objective. To determine the prevalence, risk factors, and molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) colonization at the time of admission to acute medical units and to develop a cost-effective screening strategy.Methods. Nasal and groin screening cultures were performed for patients at admission to 15 acute medical units in all 7 catchment regions in Hong Kong. All MRSA isolates were subjected to spa typing.Results. The overall carriage rate of MRSA was 14.3% (95% confidence interval [CI], 13.5–15.1). MRSA history within the past 12 months (adjusted odds ratio [OR], 4.60 [95% CI, 3.28–6.44]), old age home residence (adjusted OR, 3.32 [95% CI, 2.78–3.98]), and bed-bound state (adjusted OR, 2.19 [95% CI, 1.75–2.74]) were risk factors selected as MRSA screening criteria that provided reasonable sensitivity (67.4%) and specificity (81.8%), with an affordable burden (25.2%). spa typing showed that 89.5% (848/948) of the isolates were clustered into the 4 spa clonal complexes ...