Neoadjuvant chemotherapy for pancreatic cancer and changes in the biliary microbiome

The use of neoadjuvant chemotherapy (NAC) for pancreatic ductal adenocarcinoma (PDAC) has increased in recent years. Limited data exists on the impact of NAC on biliary microbiome.

Patients who underwent pancreaticoduodenectomy (PD) for PDAC between 2014 and 2017 were reviewed. Patients were stratified into two groups based on their NAC status for comparison.

Of 168 patients included, 63 (37.5%) received NAC. Patients who received NAC exhibited significantly increased growth of Gram-negative anaerobic bacteria (p = 0.043). Patients in the non-NAC group were more likely to grow pathogens resistant to ampicillin-sulbactam (47% vs 21%, p = 0.007), cefazolin (49% vs 28%, p = 0.040), cefoxitin (42% vs 11%, p = 0.009) and cefuroxime (26% vs 4%, p = 0.019). NAC status did not impact infectious postoperative outcomes, including SSIs.

Patients who did not receive NAC were more likely to grow pathogens resistant to cephalosporins. Perioperative antibiotic prophylaxis should be tailored to cover Gram-negative organisms and enterococci.