This study is being done to find a faster and more accurate way to tell whether the necrosis in patients with acute necrotizing pancreatitis (ANP) has become infected. In the absence of microbiological confirmation, clinicians often have to initiate empirical antibiotic therapy for suspected pancreatic infection-a practice supported by current guidelines but one that may contribute to antimicrobial resistance. In this study, the investigators will combine metagenomic next-generation sequencing (mNGS) which could improve the accuracy of infected pancreatic necrosis (IPN) diagnosis and host transcriptional response analysis which could discriminate infectious and noninfectious inflammatory syndromes. In a prospective, multicentre, cohort study, 200 consecutive patients ≥ 14 years with ANP will be enrolled at four tertiary hospitals from Novemeber 2025 to December 2026. If validated, this single-blood approach could enable early, pathogen-directed therapy, curtail unnecessary antibiotics and expedite surgical timing in ANP.

Inclusion Criteria:

1. Confirmed acute necrotizing pancreatitis (Revised Atlanta 2012) within 48 h of symptom onset
2. Age ≥14 years
3. Written informed consent

Exclusion Criteria:

1. Invasive interventions including percutaneous catheter drainage (PCD) and surgical necrosectomy have already been performed prior to admission.
2. Confirmed infection outside of pancreas, including pulmonary infection, urinary tract infection.
3. Pregnancy .
4. Acute recurrent pancreatitis

Patients with acute necrotizing pancreatitis from Xiangya Hospital Central South University, Affiliated Hospital of Guizhou Medical University, Liuzhou People's Hospital, Hunan University of Medicine General Hospital.