Antibiotic prophylaxis in skin surgery

Principles

• Most clean skin surgery requires no antibiotic prophylaxis (NICE NG125).
• Selective prophylaxis is indicated based on host risk, anatomical site, technique and wound class.
• When indicated, prophylactic antibiotic should be given 30-60 minutes pre-incision (single dose) — single peri-operative dose is usually sufficient.
• Continuing post-operative antibiotics is rarely justified.
• Antimicrobial stewardship: oversee with local microbiology guidance; document indication and duration.

Wound / patient indications

Site / wound considerations (AAD-ACMS 2008):

• Lower leg / below-knee surgery (SSI rate 7-15%).
• Wedge resection of lip / ear.
• Skin flap or large graft (face / scalp / lower limb).
• Inflamed tumour or ulcerated lesion (clean-contaminated).
• Mucosal / nasal / oral / anogenital incisions.
• Multistage Mohs with extensive debridement.
• Sentinel lymph-node biopsy or formal lymphadenectomy (high seroma risk).

Host considerations:

• Diabetes, obesity, peripheral vascular disease.
• Immunosuppression (HIV, transplant, biologics, ICI, chemotherapy).
• Prior MRSA colonisation.
• Active dermatitis at operative site.
• Frail / institutionalised patient.

Standard regimens

• First-line for skin surgery prophylaxis: oral cefalexin 2 g 30-60 min pre-procedure (single dose).
• Alternative: oral flucloxacillin 1 g pre-procedure; oral co-amoxiclav 625 mg for mixed flora (anogenital).
• Penicillin allergy: clindamycin 600 mg PO or clarithromycin 500 mg PO.
• MRSA carrier: vancomycin 1 g IV or doxycycline 200 mg PO; nasal decolonisation pre-op with mupirocin if known carrier.
• Anogenital / mucosal: co-amoxiclav 625 mg; or clindamycin + metronidazole if penicillin-allergic.
• Marine / fresh-water exposure: doxycycline ± ceftriaxone if Vibrio risk.
• Duration: single dose pre-incision; further doses only if procedure >3 hours.

Endocarditis & prosthetic-joint prophylaxis

• NICE CG64 (2008, updated 2016): routine antibiotic prophylaxis against infective endocarditis is not recommended routinely for skin surgery in patients with prosthetic valves, congenital heart disease or prior endocarditis. UK position differs from US guidance.
• Specialist cardiology input only required for highest-risk patients (acute endocarditis history, complex congenital, prosthetic valves) when skin surgery is performed at an actively infected / inflamed site.
• Prosthetic joints: BAD / BOA position — routine prophylaxis is not required for skin surgery, even within 2 years of arthroplasty; individualised decision in immunosuppressed / inflamed arthritis patient.
• Document the discussion and shared decision in the clinic letter and consent.

Practical points

• Hand hygiene, chlorhexidine 2% or povidone-iodine skin prep, drapes, sterile gloves and instruments are far more impactful than antibiotics for SSI prevention.
• Document pre-op antibiotic decision-making (or rationale for not giving) in the operation note.
• Counsel patients re wound-care signs of infection and where to seek help.
• Avoid "just-in-case" post-op courses — encourage stewardship.
• For high-risk patients on biologics / ICI, multidisciplinary review can defer elective surgery if biologic trough timing permits.