Why MRSA keeps coming back — and how to stop it

Staphylococcus aureus lives happily on human skin and in the front of the nose. Around 20–30% of the healthy population carries it persistently. MRSA carriage is less common but behaves the same way: antibiotics clear the visible abscess, the reservoir sits untouched, and a new abscess appears weeks or months later, often at a different site. Two or more infections in a year is the usual threshold for calling MRSA recurrent — and for going after the reservoir directly.

The regimen used across the NHS, the CDC and most European guidance is:

• Mupirocin 2% nasal ointment — a pea-sized amount to each nostril, twice daily, for 5 days.
• Chlorhexidine 4% body wash — used daily as a shower gel for 5–10 days, including the hair on day 1 and day 5.
• Toothbrush and razor changed at the start and end of the course.
• Bedding, towels and clothing laundered hot on day 1 and day 5.

For stubborn cases where topical treatment alone fails, some specialists add a 7–10 day course of oral rifampin plus doxycycline, but this should only be used under supervision because rifampin monotherapy rapidly selects for resistance.

One of the strongest predictors of recurrence is a colonised household contact. Randomised trials have shown that treating the whole household at once — everyone doing 5 days of mupirocin and chlorhexidine simultaneously, plus a hot laundry day — cuts one-year recurrence rates by roughly half compared with treating the index patient alone.

• Persistent nasal, throat or groin colonisation.
• A colonised household member, sexual partner or team-mate.
• Diabetes, eczema, obesity or chronic skin conditions.
• IV drug use.
• Recurrent skin trauma from work or sport.
• Repeated courses of broad-spectrum antibiotics.
• PVL-positive strains such as USA300.

Back to the prevention hub, or read about preventing MRSA at home, in hospitals, in sports and during intimacy.