Mediastinitis after cardiac surgery, from microbes to management: a systematic review

Post-sternotomy mediastinitis is a complication of cardiac surgery associated with substantial morbidity, mortality, and healthcare burden. Despite advances in surgical technique, perioperative care, and infection control, patient risk profiles and surveillance methodologies continue to drive variation in reported incidence rates. The objective of this systematic review is to review the evidence on incidence, microbiology, risk factors, prevention, and management of mediastinitis after cardiac surgery.

A systematic search of Ovid MEDLINE and EMBASE was performed from inception to October 2025 following PRISMA 2020 guidelines (registration CRD420251177438). Eligible studies included adult patients undergoing cardiac surgery with reported outcomes on mediastinitis incidence, mortality, microbiology, prevention, or management. Case reports, conference abstracts, and narrative reviews were excluded. Data were extracted on study design, population characteristics, pathogen distribution, preventive strategies, and management approaches. Due to heterogeneity in study designs and outcome definitions, a meta-analysis was not performed.

60 studies met inclusion criteria. Across over 400,000 patients, the reported incidence of mediastinitis ranged from 0.2% to 11.0%, with contemporary series typically reporting 0.5-3%. Mortality ranged from 1.5% in contemporary early-treated cohorts to 40-60% in delayed, recurrent, or fungal mediastinitis complicated by sepsis. Staphylococcus aureus and coagulase-negative staphylococci (CoNS) remained predominant pathogens, alongside methicillin-resistant strains, gram-negative bacilli, and an emerging burden of fungal and biofilm-forming organisms. Consistent risk factors included diabetes, obesity, chronic kidney disease, chronic lung disease, prolonged cardiopulmonary bypass, bilateral internal thoracic artery (BITA) harvest, high transfusion burden, and re-exploration. Preventive strategies included well-timed, weight-adjusted antibiotic prophylaxis, optimized perioperative glycemic control, skeletonized internal thoracic artery harvest, rigid sternal fixation in high-risk patients, and closed-incision negative-pressure therapy. Effective management involved early radical debridement, vacuum-assisted closure therapy, culture-directed antimicrobials, and vascularized flap coverage within multidisciplinary teams.

Post-sternotomy mediastinitis remains a preventable systemic complication. Bundled perioperative strategies, meticulous sternal technique, optimized perfusion and metabolic control, and coordinated multidisciplinary management offer the greatest potential to reduce incidence and improve outcomes. Future research should standardize definitions, refine prophylaxis bundles, optimize antimicrobial duration, and integrate advanced diagnostics for early detection of biofilm-mediated infection.