BACKGROUND: Infected walled-off pancreatic necrosis (WON) is associated with increased morbidity and mortality. Systemic antibiotics are the main treatment, but are associated with adverse reactions and risk of superinfections. This study evaluates the efficacy of local instillation of antibiotics into WON.

METHODS: We performed a retrospective cohort study of all consecutive patients with infected WON, who were treated with endoscopic transmural drainage and necrosectomy (ETDN) at a tertiary referral hospital between 2012 and 2016. A total of 91 patients were included. Patients often received concomitant intravenous and local antibiotics. Local antibiotics were added to the irrigation fluid depending on microbiological findings. A beneficial response was defined as the eradication of a microbe on subsequent culturing. Univariable and multivariable logistic regression analyses were used to evaluate antimicrobial efficacy.

RESULTS: At the first drainage 81 (86%) patients had infected and 10 sterile WON. Among patients with bacterial infections, neither local nor systemic antibiotics were associated with the eradication of microbes between first and second culture. Between the second and third culture, the use of local antibiotics was associated with the eradication of microbes (OR, 2.54; 95% CI, 1.25-5.18; p = 0.01), but not systemic antibiotics (OR, 0.75; 95% CI, 0.38-1.38; p = 0.33). Twelve patients had fungal infections treated with local amphotericin B between first and second culture. The fungus was eradicated in all 12 patients.

CONCLUSION: Local instillation of antibiotics may be a promising supplement to systemic administration.