Efficacy of the decolonization of methicillin-resistant Staphylococcus aureus carriers in clinical practice

N. Sai, C. Laurent, H. Strale, O. Denis, B. Byl

Nasal and extra nasal carriage of methicillin-resistant S. aureus (MRSA) is a pre-existing condition that often leads to invasive MRSA infection, as MRSA colonization is associated with a high risk of acquiring MRSA infection during hospital stays. Decolonization may reduce the risk of meticillin-resistant Staphylococcus aureus (MRSA) infection in individual carriers and prevent transmission to other patients. A retrospective cohort study was conducted to evaluate the effectiveness of two decolonization protocols for newly diagnosed MRSA carriage in hospitalized patients and to assess the impact of decolonization on the rate of MRSA infection. The study population consisted of all patients diagnosed as MRSA-positive between January 2006 and June 2010. Patients diagnosed as carriers were designated as requiring contact precautions by the hospital infection control team. The standing order protocol of the hospital pertaining to decolonization procedures was then applied, and all newly diagnosed patients were administered one of the two decolonization treatments outlined in the hospital protocol, with the exception of MRSA respiratory carriers (MRSA obtained from sputum or other lower respiratory tract samples). The two decolonization treatments consisted of the application of intranasal mupirocin 2 % and washing with chlorhexidine soap (40 mg/mL) (mupi/CHX) or application of intranasal povidone-iodine and washing with povidone-iodine soap (PVPI), with each treatment lasting for 5 days. Success was determined by at least three successive nose swabs and throat and other screened site swabs that tested negative for MRSA before patient discharge. A total of 1150 patients admitted to the hospital were found to be infected or colonized with MRSA. Of the 1150 patients, 268 were prescribed decolonization treatment. 104 out of 268 patients (39 %) were successfully decolonized. There was no significant success after two decolonization failures. MRSA infection rate among the successes and failures were 0.0 and 4.3 %, respectively [P = 0.04]. Our results fit well with the prescription of decolonization based on local strategy protocols but reflect a low rate of successful treatment. Although the success rate of decolonization was not high in our study, the effectiveness of decolonization on the infection rate, justifies the continuation of this strategy, even if a marginal cost is incurred.