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

Introduction: Mediastinitis is a severe infection of the mediastinum, potentially le- thal, 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. Results: Duringthestudyperiod,1508patientsunderwentcardiacsurgerywithster- notomy: 25/1508 (2%) developed a post-sternotomy surgical wound infection, in- cluding 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 co- morbidities were myocardial infarction (76%) and type II diabetes (56%). 7/25 (28%) experienced intraoperative hyperglycemia, and 10/25 (40%) had hypergly- cemia 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 onesurgicalrevision.56%receivedVAC-therapy,and52%underwentcomplexdres- sings 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-actingantibioticstofacilitatedischarge,with6/25(24%)receivingdalbavancin 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, theseinfectionsareassociatedwithprolongedantibiotictherapyandhospitalstays. Long-acting antibiotics may play a rolein treatingsternotomy wound infections, in- cluding mediastinitis with osteomyelitis.