Effect of preoperative biliary drainage on bacterial flora in bile of patients with periampullary cancer

BackgroundPatients with obstructive jaundice due to periampullary tumours may undergo preoperative biliary drainage (PBD). The effect of PBD on the microbiome of the biliary system and on postoperative outcome remains unclear. MethodsA single-centre retrospective study of patients with obstructive jaundice due to periampullary cancer, treated between July 2007 and July 2015, was undertaken. Intraoperative bile samples were obtained for microbiological analysis after transection of the common bile duct. Postoperative complications were registered. ResultsOf 290 patients treated, intraoperative bile samples were present for 172 patients (593 per cent) who had PBD and 118 (407 per cent) who did not. Contamination of bile was increased significantly in patients who underwent stenting (971 per cent versus 186 per cent in those without stenting; P < 0001). PBD resulted in a shift in the biliary microbiome from Escherichia coli in non-stented patients (45 per cent versus 192 per cent in stented patients; P = 0009) towards increased contamination with Enterococcus faecalis (9 versus 377 per cent respectively; P = 0008) and Enterobacter cloacae (0 versus 204 per cent; P = 0033). This shift was associated with a high incidence of bacterial resistance against ampicillin-sulbactam (636 per cent versus 18 per cent in patients with no PBD; P < 0001), piperacillin-tazobactam (301 versus 0 per cent respectively; P = 0003), ciprofloxacin (285 versus 5 per cent; P = 0047) and imipenem (266 versus 0 per cent; P = 0011). The rate of wound infection was higher in patients with a positive bile culture (210 per cent versus 6 per cent in patients with sterile bile; P = 0002). Regression analysis revealed the presence of Enterococcus faecium (odds ratio 283, 95 per cent c.i. 117 to 684; P = 0021) and Citrobacter species (odds ratio 509, 165 to 1571; P = 0005) as independent risk factors for postoperative wound infection. ConclusionThere are fundamental differences in the biliary microbiome of patients with periampullary cancer who undergo PBD and those who do not. PBD induces a shift of the biliary microbiome towards a more aggressive and resistant spectrum, which requires a differentiated perioperative antibiotic treatment strategy.