Pancreatic microbiota composition and diversity in pancreatitis-associated infection: a systematic review with focus on infected pancreatic necrosis.

Pancreatitis-associated intra-abdominal infection (PA-IAI), particularly infected pancreatic necrosis (IPN), is a serious complication of severe acute pancreatitis and contributes substantially to late morbidity and mortality. Sequencing-based technologies have expanded the detection of microorganisms in pancreatic infection; however, the characteristics of pancreatic microbiota and their clinical relevance have not been systematically summarized. A systematic literature search was conducted in seven electronic databases to identify studies evaluating pancreatic microbiota in patients with pancreatitis-associated infection. Studies reporting microbial composition or diversity using sequencing-based approaches were included. Study characteristics, microbial findings, diversity patterns, clinical outcomes, and methodological details were systematically extracted and synthesized. Six studies involving 235 participants were included; 188 participants contributed pancreatic or peripancreatic microbiota data. Most available evidence was derived from patients with IPN. Sequencing-based approaches generally detected a broader range of microbial taxa than conventional culture, with enteric-associated microorganisms frequently detected, while phylum-level dominance varied among studies. Reported diversity patterns varied between studies and could not be directly compared because of methodological heterogeneity. Although IPN was associated with worse clinical outcomes, current evidence did not demonstrate that specific microbial taxa or microbiota characteristics independently predicted mortality, organ failure, or treatment response. Current evidence indicates that pancreatic microbiota in pancreatitis-associated infection, particularly IPN, are characterized by frequent detection of enteric-associated microorganisms and substantial methodological heterogeneity. Sequencing-based approaches may provide additional microbiological information beyond conventional culture and may influence clinical management; however, whether sequencing-guided management changes improve antimicrobial stewardship or patient-centered outcomes remains uncertain. Future prospective studies using standardized microbiome workflows are required to determine the clinical significance of pancreatic microbial characteristics. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261295285, identifier: CRD420261295285.