The Natural History of Community-Associated Methicillin-Resistant Staphylococcus Aureus (CA-MRSA) Infections and an Evaluation of Decolonization Strategies

Infections with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) range in severity from superficial skin abscesses to invasive soft tissue infections like cellulitis and pyomyositis. There has been a large increase in the number of patients presenting to our institution with CA-MRSA infections. Colonization with S. aureus (SA) may be linked to the development of infection but data on this phenomenon are limited. The recurrence rate for CA-MRSA soft tissue infections is unknown. A variety of decolonization strategies have been used for infection prophylaxis with varying results, primarily in patients undergoing hemodialysis or surgery. This study seeks to determine the recurrence rate of soft tissue infections among patients with CA-MRSA infections and to determine a reasonable and efficacious decolonization strategy to eradicate CA-MRSA from previously infected patients.

The proposed methods for decolonization will be tested in a randomized controlled trial with four intervention arms. The intervention arms are: (1) intensive education on prevention of skin infections through improvements in personal hygiene (also serves as "control group"), (2) application of mupirocin in the nasal mucosa alone, (3) a combination of nasal application of mupirocin and chlorhexidine showers, and (4) a combination of nasal application of mupirocin and bathing in dilute bleach water. The "control" group as well as the three other arms will receive intensive hygiene education.

Decolonization with mupirocin ointment and chlorhexidine showers or dilute bleach baths in combination are likely to be more successful than either the application of nasal mupirocin ointment alone or hygiene measures alone. It is expected that these decolonization methods will result in a 50% relative reduction in MRSA colonization at 6 months.