46 Chapter 3 with endemic MRSA, mupirocin was only marginally effective [26]. In particular, throat carriage is associated with failure of topical eradication treatment [30]. In a small study on Swedish outpatients with MRSA throat carriage, topical therapy led to successful eradication in only 13%, as compared with 61% when topical therapy was combined with systematic antibiotics [31]. Positive household contacts were simultaneously treated. A similar outcome was reported in outpatient MRSA carriers in Canada initially; however, after 1 year, success rates with and without systemic antibiotics were found to be equal [32]. Canada is a high-endemic area, and because no screening of household contacts or genotyping was performed, it remains undetermined whether this outcome resulted from recolonization with a different strain, or long-term failure of eradication treatment. Discriminating between nasal-only and extra-nasal MRSA colonization to guide optimal eradication therapy seems appropriate considering the abovementioned studies and from a pathophysiologic perspective. This distinction is also made in the Dutch MRSA eradication guideline, where mupirocin-sensitive, nasal-only MRSA carriage with intact skin is considered ‘uncomplicated’ and is recommended to be treated with topical agents only. MRSA carriers with extra-nasal colonization or other risk factors for (topical) treatment failure, e.g. active skin lesions and foreign body material, are considered ‘complicated’ and are treated with additional systemic antimicrobial agents [33]. This specific approach led to sustained decolonization in 85% of carriers after 1 year of follow-up [23]. MRSA carriage of household members was the most frequently encountered risk factor for CO-MRSA infections in Denmark between 1999 and 2006 [34], and was associated with failure of eradication treatment [22]. This emphasizes the need for screening and simultaneous eradication of all positive household members, especially in case of treatment failure. In general, infection prevention and control measures are crucial in preventing further spread of MRSA [35], but are not included in this review. Efficacy of topical decolonization therapy The most commonly used topical treatment for S. aureus decolonization is mupirocin nasal ointment, which achieves its antimicrobial effect by inhibiting bacterial protein synthesis. It is often combined with daily antiseptic body wash. Mupirocin nasal ointment was proven to be effective in MSSA decolonization in the 1980s and 1990s [36-45]. In a systematic review that included studies analysing both MSSA and MRSA colonization, mupirocin resulted in negative MRSA cultures in 94% of patients after 1 week [25]. This percentage decreased to 65% after (mid- to long-term) follow-up.
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