With this study, the investigators want to determine whether a fast identification of microorganisms causing intra-abdominal infections in patients with suspected hollow organ perforation or peritonitis is possible using a multiplex PCR system (Unyvero A50), a method that allows rapid detection of predefined bacterial and fungal targets directly from clinical samples. Therefore, intra-abdominal peritoneal fluid samples collected during surgery will be analyzed by multiplex PCR and by conventional microbiological culture. The investigators want to determine whether multiplex PCR diagnostics could provide results faster than conventional microbiological methods and deliver additional information on pathogen detection.

This prospective observational study evaluates a rapid multiplex PCR system (Unyvero A50, Curetis) as an adjunct to conventional microbiological culture (cMB) in adult patients undergoing surgery for suspected hollow viscus perforation or peritonitis. During surgery, two intra-abdominal peritoneal fluid samples will be collected. One sample will be processed by routine aerobic and anaerobic culture at the microbiology laboratory. The second sample will be analyzed postoperatively using multiplex PCR at the surgical intensive care unit according to the manufacturer's instructions.

The study will compare turnaround time and concordance of pathogen detection between multiplex PCR and cMB. Additional descriptive analyses will include pathogen group distributions, polymicrobial findings, and results by anatomical site of perforation. Resistance markers detected by PCR will be recorded descriptively. Invalid PCR results will be documented and excluded from paired analyses.

Inclusion Criteria:

• suspected hollow organ perforation
• suspected peritonitis
• patient underwent surgical treatment
• microbiological testing of intra-abdominal fluid was needed

Exclusion Criteria:

• patient in moribund conditions
• patient already enrolled in an interventional clinical trial
• patient under 18

Patients with suspected hollow organ perforation at the University Medical Center Göttingen, who underwent surgical treatment and were admitted to the intensive care unit for postoperative care