The purpose of this study is to determine if mupirocin 2% in polyethylene glycol (PEG) ointment [Treatment Arm] is effective in preventing moderate to severe re-infection with Staphylococcus aureus compared with treatment with polyethylene glycol (PEG) ointment [Placebo Arm].

Treatment of staphylococcal carriage with the topical antibiotic, mupirocin, has led to decreased infections in some hemodialysis patients and intensive care unit (ICU) patients. However, most of these studies were not placebo controlled and only certain subsets of patients benefited. Relapse of colonization, generally within 90 days after treatment is stopped, presumably with increased risk of infection, approaches 50%. Continuous use of mupirocin on daily, three times weekly, or weekly basis has resulted in increased resistance to the drug. Despite this lack of evidence, the use of mupirocin has become commonplace because it is perceived as an effective and simple means to prevent infection. In a National Institutes on Aging/Claude D. Pepper Older Americans Independence Center (NIA/OAIC)-sponsored proposal, we found that a 2 week treatment regimen with mupirocin ointment was effective in decolonizing older chronically ill nursing home residents of S. aureus when compared with placebo ointment. Decolonization began to decline by 3 months post-treatment, and resistance occurred only once in 52 treated patients. That study was not powered to detect differences in infection between the 2 study groups; the end point was eradication of colonization. However, a trend towards reduction in staphylococcal infection with mupirocin was seen. In addition, there were more therapeutic failures in residents who were colonized with methicillin-resistant S. aureus (MRSA) than methicillin-sensitive S. aureus (MSSA). We hypothesize that intermittent treatment with mupirocin ointment every 3 months may be an effective means of preventing recolonization and infection with S. aureus. We propose to study a patient population that has already had treatment for severe S. aureus infection and is at significant risk for a subsequent infection. Patients will receive mupirocin 2% polyethylene glycol (PEG) ointment [Treatment Arm] or polyethylene glycol (PEG) ointment [Placebo Arm] for 14 days every 3 months. The effect of these two regimens on S. aureus re-infection, re-colonization, and development of mupirocin resistance will be assessed.

Inclusion Criteria:

• All patients who receive care at Ann Arbor VA Medical Center, University of Michigan Medical Center, or St. Joseph Mercy Hospital, Ypsilanti who have been hospitalized for documented S. aureus infection will be eligible for enrollment. Staphylococcal infections may be community or hospital-acquired. Patients with S. aureus infection will be identified on a daily basis with the assistance of the Infection Control Practitioner, the Clinical Microbiology Laboratory, the Infectious Diseases Consultation Services, and Infectious Diseases physicians caring for patients in their offices.
• Patients will provide written informed consent. The patient's guardian or next of kin will be contacted for informed consent in the event that the patient is incapable of doing so.

Exclusion Criteria:

• Patients who are unable to cooperate with treatment or follow-up.
• Patients who are not likely to survive beyond one month or those who are transferred back to another acute care hospital.
• Patients who require treatment with rifampin will be excluded since this drug is effective in decolonization of some staphylococcal carriers.
• Patients with known hypersensitivity to mupirocin ointment or polyethylene glycol base.
• Patients with ulcers obviously related to pressure will be excluded because they are frequently large, difficult to keep clean, and infections are difficult to diagnose.
• Patients with small vascular or neuropathic ulcers < 3 cm in circumference and < 2 cm in depth may be enrolled.
• Pregnant women.

Duration of the study - 18 months

A questionnaire was administered by study personnel at each visit. Patients who did not show for visits were contacted by phone and mail at regular intervals by study personnel. Chart reviews were conducted for patients who did not show or respond.

The study is underpowered to detect differences between the two treatment arms. We achieved only 75% of target enrollment, and 41.1% dropped out before reaching a primary endpoint. Our re-infection rate was also lower than anticipated (14.4%).