The microbiology of infected pancreatic necrosis in the era of minimally invasive therapy.

We aimed to determine the microbiology of infected walled-off pancreatic necrosis (WON) in an era of minimally invasive treatment, since current knowledge is based on surgical specimens performed over two decades ago. We retrospectively analyzed a prospectively maintained database of patients who were treated for symptomatic WON using combined endoscopic and percutaneous drainage between 2008 and 2017. Aspirates from WON at initial treatment were evaluated. One hundred eighty-two patients were included with a mean age of 56 of whom 67% were male. Culture results were obtained at a median of 45 days from onset of acute pancreatitis of which 41% were infected. Candida spp. accounted for 27%; yet, multidrug-resistant organisms were found in only five patients. Approximately 64% were transferred to our institution for continuation of care. Of those, 55% were infected, most frequently with Candida spp., Enterococcus spp., and coagulase-negative Staphylococcus. Patients seen and admitted initially at our institution had milder forms of pancreatitis, fewer comorbidities, and 85% had symptomatic sterile WON. Empiric antibiotic use successfully predicted infection 70% of the time. Multivariate analysis demonstrated that elderly age, severity of pancreatitis, and prior use of antibiotics were indicators of infection. Necrotic pancreatic tissue remains sterile in the majority of cases treated with minimally invasive therapy, enabling judicious selection of antibiotics. Candida and Enterococcus spp. were common. Patients at highest risk for infection were previously treated with antibiotics and those transferred from outside institutions.