MRSA decolonization: success rate, risk factors for failure and optimal duration of follow-up.

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) decolonization is a widely established, though controversial part of many MRSA controlling strategies. The aim of this study was to evaluate our decolonization success rate, identify the risk factors for decolonization failure and determine the optimal duration of follow-up in our low MRSA prevalence setting (2.6 % of isolates).

METHODS: Every patient with newly detected MRSA colonization or infection between January 2007 and December 2009 was recruited to the study. The MRSA strategy of our institution (a 700 bed tertiary hospital in eastern Switzerland) consists of a 5-day regimen of nasal mupirocin ointment, chlorhexidin mouth rinse and whole body wash with didecyldimonium chloride. Systemic antibiotics are usually not added to the regimen.

RESULTS: We determined a MRSA decolonization success rate of 65 % (33/51) after a median follow-up of 13 months [i.e. a tripling of the spontaneous clearance rate of 22 % (6/27) in the non-decolonized group]. The most important risk factor for decolonization failure was colonization of the respiratory tract [odds risk (OR) 9.1, 95 % confidence interval (CI) 1.2-66.7], as well as isolation of MRSA spa-type 002 ([R 5.8, 95 % CI 1.0-33.3). Of all the episodes of MRSA recurrence, 88 % (14/16) were detected within 270 days after decolonization.

CONCLUSION: High MRSA decolonization success rates can be achieved without the routine use of oral antibiotics. A time period of 1 year after decolonization seems to be a reasonable duration of follow-up in our setting. We encourage other institutions to take into account local MRSA epidemiology (e.g. predominance of certain subtypes) for the management of MRSA patients.