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Mupirocin-resistant, methicillin-resistant Staphylococcus aureus: does mupirocin remain effective?
Elaine S Walker1, Jose E Vasquez, Roy Dula
1James H Quillen Veterans' Affairs Hospital, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614, USA.
Infection Control and Hospital Epidemiology
|June 6, 2003
Summary
Mupirocin ointment effectively cleared susceptible MRSA nasal colonization, but resistant strains often persisted, indicating treatment failure. Pre-treatment susceptibility testing is crucial for effective MRSA infection control programs.
Area of Science:
- Infectious Diseases
- Microbiology
- Clinical Pharmacy
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) nasal colonization is a significant public health concern.
- Mupirocin is a topical antibiotic commonly used to decolonize MRSA.
- The emergence of mupirocin resistance in MRSA strains poses a challenge to treatment efficacy.
Purpose of the Study:
- To evaluate the effectiveness of mupirocin ointment in reducing nasal colonization of both mupirocin-susceptible (MS) and mupirocin-resistant (MR) MRSA.
- To assess the persistence of MRSA strains after mupirocin treatment.
Main Methods:
- Prospective study involving 40 hospitalized patients with MRSA nasal colonization.
- Patients received topical 2% mupirocin ointment twice daily for 5 days.
- Nasal cultures were obtained pre-treatment and at multiple time points post-treatment for susceptibility testing and DNA typing.
Main Results:
- Mupirocin achieved high clearance rates for MS MRSA (78.5% on day 3, 91% sustained).
- Clearance rates were significantly lower for mupirocin-resistant MRSA, particularly high-level resistant strains (27.7% on day 3, 25% sustained).
- Persistent MRSA isolates typically maintained their original DNA patterns, suggesting treatment failure rather than re-colonization.
Conclusions:
- Mupirocin is effective against mupirocin-susceptible MRSA but shows limited efficacy against mupirocin-resistant strains.
- High-level mupirocin resistance in MRSA is associated with treatment failure.
- Routine susceptibility testing for mupirocin is recommended before implementing mupirocin-based infection control strategies for MRSA.