Duration of Antibiotic Therapy in Necrotizing Soft Tissue Infections: Shorter is Safe

Early debridement improves outcome in necrotizing soft tissue infection (NSTI), but there is no consensus on duration of antimicrobial therapy. We recently changed practice to discontinue antibiotic agents early with a goal of 48 hours after adequate source control. We hypothesized that discontinuing antibiotic agents after a short course is safe in the treatment of NSTI. This was a prospective study of patients with NSTI comparing short duration of antibiotic agents to a control population after a change in practice. In 2018 we began discontinuing antibiotic agents within 48 hours of source control (absence of cellulitis and no evidence of active infection). Previously, antibiotic duration was at the discretion of the attending surgeon (generally 7-10 days). Patients were excluded from analysis if they were initially debrided at a referring facility, immune compromised, or died prior to source control. Patient characteristics and outcomes were evaluated. The primary outcome was treatment failure requiring antibiotic agents to be restarted with or without further debridement of infected tissue. Secondary outcomes included the duration of antibiotic therapy after source control. We evaluated 151 patients; 119 admitted between January 1, 2011 and January 31, 2018 (PRE) and 32 admitted after January 31, 2018 (POST). Patients were not statistically different regarding characteristics, admission physiologic variables, and comorbidities. The median duration of antibiotic agents after source control in the PRE group was 180.3 hours (interquartile range [IQR], 100.7-318.8) versus 48 hours (IQR, 32.3-100.8) in the POST group (p < 0.01). Patients in each group were treated as described above, and treatment failure occurred in seven (5.9%) PRE patients and two (6.3%) POST (99.3% post hoc power at non-inferiority limit 20%, significance p < 0.05). Thirty-day all-cause mortality was not different between groups (6.7% vs. 6.3%; p = 0.94). Short-duration (48 hours) antibiotic agents after NSTI source control is as safe and effective as a longer course.