A Focus on Inflammatory and Bacterial Biomarkers in Secondary Peritonitis

Secondary peritonitis is a life-threatening intra-abdominal condition arising from gastrointestinal perforation, chemical injury, or catheter-related infections, characterized by marked heterogeneity in presentation and progression. Major subtypes include stercoraceous peritonitis with fecal contamination, fibrinous peritonitis triggered by bile or gastric contents, peritoneal dialysis-associated infections, and pancreatitis-associated chemical peritonitis. Regardless of etiology, these conditions share profound local and systemic inflammatory responses, contributing to high morbidity and mortality. Biomarkers such as procalcitonin (PCT), interleukin-6 (IL-6), high mobility group box 1 (HMGB1), C-reactive protein (CRP), lipopolysaccharide (LPS), neutrophil-to-lymphocyte ratio (NLR), and neutrophil gelatinase-associated lipocalin (NGAL) have emerged as tools for early diagnosis, subtype stratification, and monitoring of therapeutic response. Their prognostic value is particularly relevant in peritoneal dialysis and postoperative intensive care. Advances in multi-omics, patient-derived organoids, peritoneum-on-chip models, and microbiota profiling are reshaping understanding of peritoneal pathophysiology, revealing cellular heterogeneity, immune-microenvironment interactions, and mechanisms of fibrotic remodeling. Key translational challenges include assessing whether omics-derived signatures can predict the need for early re-laparotomy or the risk of abdominal compartment syndrome. Integration of high-dimensional biomarker profiling with mechanistic and functional studies promises a new era of precision medicine in secondary peritonitis, enabling risk-adapted interventions, complication prevention, and tailored strategies to improve outcomes.