21 Intraoperative microbiological study of biliary flora in patients undergoing pancreaticoduodenectomy. How does preoperative biliary drainage affect?

Abstract Introduction Surgical site infection (SSI) is the most common healthcare-associated infection. Patients undergoing pancreaticoduodenectomy (PD) may require preoperative biliary stent placement, which is a risk factor for postoperative SSI. Scientific Justification: Historically, antibiotic prophylaxis in our hospital was the same for all patients undergoing PD (cephalosporin). Our historical rate of organ-space SSI was twice higher in patients with biliary stents compared to those without (28% versus 14%). We modified the prophylaxis specifically with piperacillin-tazobactam in patients with preoperative biliary stents, intending to reduce postoperative SSI. Objectives Main objective: To confirm if, in our hospital, biliary microbiology differs between patients undergoing PD based on whether they have preoperative biliary stents or not. Secondary objectives: 1-To evaluate if perioperative antibiotic treatment targeted according to the expected flora, based on the presence or absence of biliary stents, reduces SSI. 2-To evaluate if controlling SSI in patients undergoing resection for pancreatic ductal adenocarcinoma and periampullary tumors allows timely initiation of adjuvant treatment. Study Design Observational, single-center, retrospective, analytical study of two cohorts of patients who underwent PD in which bacterobilia is analyzed between two groups: NP (no biliary prosthesis) and P (with biliary prosthesis), and infectious complications after applying directed perioperative antibiotic treatment. The antibiotic regimens used were cefotaxime and metronidazole for group NP, and piperacillin-tazobactam for group P. Analysis of the patients in the subgroup (pancreatic adenocarcinoma and periampullary tumors) includes the percentage of adjuvant therapy and survival rates. Overall sample size: N = 90, 45 per group. The double number of patients from the NP group (90) is included as the control group. Results Between January 2014 and December 2021, 127 patients underwent PD (84 NP and 43 P). The intraoperative culture was positive in 16.7% (NP) versus 76.7% (P, P < 0.01), with 72.7% of polymicrobial cultures in the P group. The microorganisms isolated in the NP group were Enterobacterales (10.7%) and Enterococcus (7.1%), without Candida. In the P group, there was an increase in Enterococcus (48.8%), Enterobacterales (51.2%), and Candida (16.3%) (P < 0.01). There were no differences in morbidity or mortality between the two groups. The organ-space SSI rate was 15.5% in the NP group and 13.9% in the P group (not significant). The multivariate analysis revealed that significant risk factors for developing SSI were intraoperative bile culture positive for Enterobacterales (OR 3.7; P = 0.02), presence of pancreatic fistula (OR 5.5; P = 0.04), and surgical reintervention (OR 27.2; P < 0.01). The agreement between intraoperative and postoperative bile cultures was 80% in the P group versus 13.3% in the NP group (P = 0.002). Among the analyzed cancer patients, 76% initiated adjuvant treatment, with 95% of them starting within the optimal time, with no differences between groups, as well as survival. Conclusions The biliary flora differs in patients with biliary stents, with a higher presence of Enterobacterales, Enterococcus, and Candida. After applying perioperative antibiotic treatment targeted at the expected biliary microbiology, there were no observed differences in SSI or delays in the initiation of adjuvant therapy. The need to change antibiotic prophylaxis in patients undergoing DPC is suggested.