Treating invasive MRSA wound infection

Signs include increasing pain after the second or third postoperative day, spreading redness beyond the incision, warmth and swelling, purulent or foul discharge, wound edges separating, fever, and rising inflammatory markers. Deep infection may show little on the surface, with pain, fever and a raised CRP as the only clues; ultrasound, CT or MRI is used to look for a collection.

Diagnosis rests on deep tissue samples taken at exploration rather than a superficial swab, which often grows colonising skin flora instead of the true pathogen.

Source control means physically removing what the antibiotic cannot reach: opening the wound, excising necrotic tissue, washing out collections, removing infected sutures or mesh, exchanging or removing a prosthesis, and taking out infected intravascular lines. It may be staged, with repeat debridement every 24–72 hours until the tissue bed is clean. Negative pressure dressings and delayed closure are used afterwards.

Necrotising infection — severe pain, skin blistering or blackening, crepitus, rapid progression — is a surgical emergency needing immediate exploration alongside linezolid or clindamycin for toxin suppression.

• Superficial surgical site infection: after drainage, oral co-trimoxazole or doxycycline for 7–14 days.
• Deep or complicated wound infection: intravenous vancomycin or daptomycin, with ceftaroline or teicoplanin as alternatives, for 2–4 weeks.
• Bone involvement (osteomyelitis): six weeks or more of intravenous therapy, or an equivalent oral regimen with good bone penetration.
• Implant or prosthetic joint infection: a companion drug plus rifampicin for its activity in biofilm, typically 3–6 months, with debridement or implant exchange.

Long outpatient courses are increasingly delivered with dalbavancin where keeping an intravenous line is impractical.

Pre-operative screening and decolonisation, chlorhexidine showering, appropriate surgical prophylaxis, and strict dressing hygiene all cut the rate of MRSA surgical site infection. See hospitals and surgery and decolonisation.