384. Denosumab-Related Osteonecrosis of the Jaw: an Emergent and Potentially Complex Bone and Joint Infection

Abstract Background Osteonecrosis of the jaw is a known complication of antiresorptive treatment, like bisphosphonate. More recently, denosumab was validated as a treatment in the osteoporosis and bone metastasis. Its mechanism is different from bisphosphonate but induces also a decrease of bone resorption and a risk of osteonecrosis of the jaw. In case of treatment failure by a dental surgeon or in complex cases, patients could be addressed to a bone and joint infection (BJI) reference center. The aim of this study was to analyze microbiology, as well as surgical and medical care of patients who present denosumab-related osteonecrosis of the jaw (DRONJ) and who were treated in a bone and join reference center. Methods All patients managed in our BJI reference center between January 2013 and December 2018 for a DRONJ were included in our retrospective observational monocentric cohort. Results Twelve patients (median age 71; ratio M/W 0.7) with a DRONJ (metastatic cancer, n = 10 (83%)) in grade 3 (n = 5), 2 (n = 4), 1 (n = 3) were included. Only 3 patients (25%) had a dental health control before initiating the treatment by denosumab and 7 patients (58%) had a dental surgical procedure done before the DRONJ. Eleven patients had a bone exposure, treated at least with a scaling and mucosal closure at the same time. All infections with bacterial cultures (n = 11 (91%)) were polymicrobial, including 8 (72%) with Streptococcus spp; 8 (72%) with anaerobia including 2 (18%) with Actinomyces; 5 (45%) with Staphylococcus spp; 5 (45%) with enterobacteria; 3 (27%) with Candida spp; 2 (17%) with a non-fermentative Gram-negative bacilli and 7 (64%) with others bacteria. All patients (n = 12) received a betalactam, 8 (66%) a lincosamide or a synergistin, 5 (41%) an antifungal, 5 (41%) metronidazole, 4 (33%) a fluoroquinolone, 3 (25%) a glycopeptide and 2 (17%) other antibiotics. The median follow-up was 6 months. Eight patients were cured after a medico-surgical care and a median duration of antibiotics of 97 days (including 28.5 days in intravenous). 2 patients required a suppressive antibiotic treatment, 1 relapsed at a distance of the treatment and 1 died from some other causes. Conclusion DRONJ is a potential complex BJI, for which some patients could benefit from medical care in a BJI reference center. Disclosures All authors: No reported disclosures.