The microbiological landscape of infected walled-off necrosis and pancreatic pseudocysts: a systematic review and meta-analysis

Abstract Introduction Pancreatic fluid collections (PFCs) are severe local complications of acute pancreatitis that frequently become infected with bacterial and fungal pathogens. However, evidence regarding the prevalence and distribution of these microorganisms remains limited. We aimed to characterise the microbiological profile of infected PFCs undergoing minimally invasive drainage. Methods We conducted a systematic search including studies reporting on the microbiological profile in patients undergoing endoscopic or percutaneous drainage for infected walled-off necroses (WON) or pancreatic pseudocysts (PPC). The analysis was based on pooled proportions with 95% confidence intervals (CIs). The protocol was registered in PROSPERO (CRD420251182985). Results Overall, 31 studies were analysed, involving 1,286 patients with culture-positive infections. Escherichia coli (21%; CI:13–31%) and Enterococcus spp . (20%; CI:12–33%) were the most prevalent bacteria in infected WON, while Candida spp . were also frequently detected (20%; CI:11–33%). Multidrug-resistant organisms were present with 24% pooled prevalence in infected patients (CI:10–50%). Regional stratification found notable variations in pathogenic distribution. In Europe, Candida spp. (38%; CI:23–56%) and Enterococcus spp. (35%; CI:21–52%) predominated, while in Asia, Escherichia coli (29%; CI:11–56%) and Klebsiella spp. (27%; CI:14–47%) were more common. In infected PPC, Escherichia coli was the leading pathogen (29%; CI:8–65%), followed by Staphylococcus spp. (25%; CI:4–75%) and Klebsiella spp. (18%; CI:2–68%). Conclusion Infected WON and PPC exhibit a diverse microbiological profile, with a high prevalence of enteric and fungal organisms and marked heterogeneity across regions and sampling modalities. Recognition of regional pathogenic distribution and pathogen identification may help guide better antibiotic treatment and strengthen antimicrobial stewardship in infected PFCs, warranting further prospective evaluation.