The Natural History of Community-Associated MRSA Infections and 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.

Inclusion Criteria:

- Any patient who presents with at least one serious skin or soft tissue infection
requiring incision and drainage at an affiliated institution or clinic in the St.
Louis metropolitan area

Exclusion Criteria:

- Patients with permanent indwelling catheters or percutaneous medical devices

- Patients with a history of dialysis treatments, long term care facility admission, or
presents with a surgical wound infection within the past year

- Patients who are pregnant