This observational study aims to evaluate the penetration of intravenously administered antibiotics into pancreatic fluid collections in patients with suspected infected walled-off pancreatic necrosis (WOPN). In selected patients undergoing percutaneous or endoscopic drainage of the collection as part of their clinical care, a small sample of pancreatic fluid will be collected and analyzed to determine the concentration of the administered antibiotic.

At the same time, a blood sample will be taken to assess the antibiotic concentration in plasma. By comparing the concentrations in pancreatic fluid and plasma, the study seeks to determine the extent to which different antibiotics (e.g., meropenem or piperacillin-tazobactam) reach the site of infection within the pancreas.

All procedures performed as part of the study, with the exception of the antibiotic concentration measurement, are standard components of routine care for patients with complicated acute pancreatitis. Participation in the study does not alter the diagnostic or therapeutic management of the patient. Patients provide written informed consent before enrollment.

The results of this study may help optimize antibiotic dosing in patients with infected pancreatic collections and contribute to more effective and individualized treatment strategies in the future.

Inclusion Criteria:

• Age ≥ 18 years
• Signed informed consent
• Undergoing percutaneous or endoscopic drainage/puncture of a pancreatic fluid collection

Exclusion Criteria:

- Failure or refusal to sign informed consent

Adult patients hospitalized with past or ongoing acute pancreatitis undergoing drainage or puncture of suspected infected pancreatic fluid collection. Patients are recruited from the University Hospital Brno. Approximately 40 participants are expected.