Groin dissections in skin cancer: Effect of a change in prophylactic antibiotic protocol.

Objectives: To determine whether groin dissection surgical site infection (SSI) incidence changed with shorter post-operative antibiotic prophylaxis.

Background: Post-operative prophylaxis changed due to antimicrobial stewardship, from regular oral antibiotics until drain removal, to three intravenous doses. Both groups had a single intravenous dose at induction.

Methods: A prospective database of groin dissections for metastatic skin cancer was retrospectively reviewed for SSI according to Public Health England criteria. Eighty groin dissections in 79 consecutive patients were included: 40 had oral antibiotics until drain removal [mean 26±7 (range 19-36) days] and 39 had three post-operative intravenous doses.

Results: Longer prophylaxis was associated with lower SSI incidence [10 (25%) versus 21 (54%), odds ratio (OR) 3.50, 95% confidence interval (CI) 1.34-9.08, p = 0.009], fewer deep infections [5 (13%) versus 16 (41%), OR 4.89, 95% CI 1.57-15.13, p = 0.004], fewer readmissions for infection [5 (13%) versus 15 (38%), OR 4.38, 95% CI 1.40-13.65, p = 0.008], but similar seroma incidence [18 (45%) versus 16 (41%), OR 0.85, 95% CI 0.35-2.07, p = 0.72] and wound dehiscence [7 (18%) versus 5 (13%), OR 0.69, 95% CI 0.20-2.40, p = 0.56]. BMI ≥30 (n = 21) was associated with SSI, occurring in 13 of 21 (62%) (OR 3.859, 95% CI 1.34-11.10, p = 0.01). Median infection onset was 22 days (IQR 12-27) versus 17 (IQR 13-22), (p = 0.53). Multiple organisms were cultured in 21 of 31 (68%) patients with positive microbiological samples.

Conclusions: SSI rates doubled with shorter prophylaxis; deep infections and readmissions for infection tripled. Obesity was independently associated with infection. Seroma and wound dehiscence incidence were unchanged. Infections mainly occurred in the third week after surgery and were polymicrobial.