The risk factors for community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infection were not well understood. The objective of this study was to identify risk factors associated with CA-MRSA infection in Hong Kong.

We carried out a matched case control study. Cases and controls were recruited from 14 acute public hospitals in Hong Kong. One control was individually matched to one case based on sex, age, admission date and ward location. We interviewed each case and control by telephone using a standard questionnaire. We used a conditional logistic regression model for multivariate analysis.

We successfully recruited 127 pairs of matched case and control. We found that sharing of personal items with other persons had a higher risk of CA-MRSA infection (Adjusted matched odds ratio [aOR]: 4.71, 95% confidence interval [CI] 1.43–15.59). On the other hand, patients who had frequent hand washing practice (aOR: 0.21, 95%CI 0.06–0.72) and those who reported history of acne (aOR: 0.12, 95%CI 0.02–0.74) had a lower risk of CA-MRSA infection.

We concluded that sharing of personal items with other persons is a risk factor for CA-MRSA infection while frequent hand washing is a protective factor against the infection.