P24. Clinical features and outcomes of post-surgical sternotomy infections

Introduction Mediastinitis is a severe infection of the mediastinum, potentially lethal, and often is a surgical complication following sternotomy. Definitions of this complication include superficial infection (SI), mediastinitis without osteomyelitis (MN), and with osteomyelitis (MO).1–4 Study Objective To analyze the prevalence and clinical characteristics of post-sternotomy infections. Materials and Methods This prospective observational study includes patients with surgical wound infections following sternotomy, hospitalized between January 2020 and December 2024, at the Department of Cardiosurgery of Policlinico Umberto I in Rome, Italy. Infections were classified as SI, MN, and MO according to Oakley.1 Results During the study period, 1508 patients underwent cardiac surgery with sternotomy: 25/1508 (2%) developed a post-sternotomy surgical wound infection, including 13 MO (52%), 7 MN (28%), and 5 SI (20%). The median age was 69 years (IQR 63–76); median BMI was 26.01 (IQR 23.70–27.71). The most common comorbidities were myocardial infarction (76%) and type II diabetes (56%). 7/25 (28%) experienced intraoperative hyperglycemia, and 10/25 (40%) had hyperglycemia in the first 48 hours post-surgery. 6/25 (24%) were polymicrobial infections, and 15/25 (60%) were monomicrobial. The most frequently isolated pathogens were Gram-negative bacteria (48%), S. epidermidis (32%), and S. aureus OXA-S (24%). 15/25 (60%) underwent a surgical revision, and 7/25 (28%) had more than one surgical revision. 56% received VAC-therapy, and 52% underwent complex dressings with an open sternum. All patients received targeted intravenous antibiotic therapy. The patients received antibiotics for a median of 21 days (IQR 16.5–30.3), with a median hospital stay of 55 days (IQR 47–79). 7/25 (28%) were treated with long- acting antibiotics to facilitate discharge, with 6/25 (24%) receiving dalbavancin and 1/25 (4%) receiving oritavancin. The 90-day survival rate was 23/25 (92%), with only one case of infection recurrence (4%) and subsequent hospitalization. Conclusions The prevalence of sternotomy wound infections was 2%. Gram-negative bacteria represent a significant cause of infection. Although rare, these infections are associated with prolonged antibiotic therapy and hospital stays. Long-acting antibiotics may play a role in treating sternotomy wound infections, including mediastinitis with osteomyelitis.