Antibiotic coverage in biliary-stented pancreatoduodenectomy: Real-world evidence supporting piperacillin tazobactam over ampicillin sulbactam

BackgroundPreoperative biliary stenting alters biliary colonization and may reduce the effectiveness of perioperative antibiotic prophylaxis in pancreatoduodenectomy. Although broader-spectrum regimens have been associated with improved infectious outcomes, their microbiological adequacy in routine clinical practice remains poorly defined. We therefore evaluated the real-world adequacy of a prolonged ampicillin-sulbactam protocol, its association with infectious outcomes and survival, and the potential impact of a universal piperacillin-tazobactam strategy. MethodsWe analyzed all consecutive patients who underwent elective pancreatoduodenectomy from 2002 to 2023 at our tertiary center. Demographic, operative, microbiological, and outcome data were retrieved from a prospectively maintained database. Patients were stratified by stent status. Adequacy of prophylaxis was defined as the full in vitro susceptibility of all bile isolates. The outcomes included 30-day infectious morbidity, clinically relevant POPF, PPH, DGE, reoperation, 30- and 90-day mortality and long-term survival. A coverage simulation was performed to compare ampicillin-sulbactam with a hypothetical universal piperacillin-tazobactam. Statistical methods included chi-square/Fishers exact tests, Mann-Whitney U tests, Cox models, McNemars test and Poisson regression. ResultsOf 956 patients, 424 (44%) had a biliary stent. Technical complications were comparable between groups, and rates of POPF and PPH were not increased. However, infectious morbidity was higher in stented patients, including sepsis (RR 1.62, 95% CI 1.05-2.51) and postoperative cholangitis (RR 2.20, 95% CI 1.36-3.56). Thirty- and 90-day mortality were increased (RR 2.88 and 2.73) but lost significance after adjustment. Bile cultures predominantly yielded Enterococcus and Enterobacterales with low ampicillin-sulbactam susceptibility. Overall adequacy was 21.7%. Among patients with bile cultures (n = 474), ampicillin-sulbactam covered 43.7% (207/474) versus 81.2% (385/474) with piperacillin-tazobactam; in stented patients with cultures (n = 397), coverage increased from 41.8% to 78.1%. Adequate ampicillin-sulbactam coverage was not associated with reduced infectious outcomes in Poisson models. ConclusionPreoperative stenting creates a polymicrobial, partially resistant biliary niche that ampicillin-sulbactam does not sufficiently cover. Our data shows that a piperacillin-tazobactam strategy substantially improves coverage and was therefore implemented at our center. Core message- Stented patients exhibit a distinct infectious risk profile characterized by Enterococcus-and Enterobacterales-dominated bile colonization rather than increased rates of technical complications. - In stented patients, real-world microbiological coverage of ampicillin-sulbactam was limited, and in vitro susceptibility did not independently translate into reduced postoperative infectious morbidity. - Broader prophylaxis, such as piperacillin/tazobactam, aligns with the actual flora and nearly doubles theoretical coverage, addressing the mismatch between stent-associated biofilms and narrow regimens.