Methicillin-resistant Staphylococcus aureus and antimicrobial use in Belgian hospitals

OBJECTIVE: To investigate relationships between the incidence of methicilli n-resistant Staphylococcus aureus (MRSA) and the use of different classes o f antimicrobials in Belgian hospitals. DESIGN: Using Pearson correlation coefficients, the number of new nosocomia l MRSA-colonized or -infected patients in the second half of 1994 and the f irst half of 1995 reported by the national MRSA surveillance program was co mpared with use of various antimicrobial classes as reported by the Nationa l Institute for Sickness and Disability Insurance. Relationships between di fferent classes of antimicrobials were evaluated in a correlation matrix. M RSA incidence, antimicrobial use, and potential confounding factors were in cluded in a multiple linear regression analysis. SETTING: 50 hospitals in Belgium. RESULTS: The use of a number of different classes of antimicrobials was int errelated. In the multivariate analysis, the incidence of nosocomial MRSA i ncreased with increasing use of ceftazidime and cefsulodin (P=.0003), amoxi cillin with clavulanic acid (P=.02), and quinolones (P=.005). No associatio n was found between MRSA incidence and total antimicrobial use. CONCLUSIONS: The relationships between antimicrobial use and MRSA are compl ex. Interventions aimed at promoting more rational prescribing patterns sho uld be supported by adequate experimental and epidemiological evidence. Adv ice for preventing and controlling MRSA has focused mainly on hygienic meas ures and precautions to avoid cross-transmission; the role of relieving ant imicrobial pressure needs to be clarified.