Rare Nocardia cyriacigeorgica osteomyelitis in an immunocompromised elderly patient: A case highlighting treatment challenges.

Nocardia cyriacigeorgica, an emerging pathogen, poses significant risks to immunocompromised patients. We report a rare case of N.cyriacigeorgica-induced osteomyelitis in an 82-year-old woman undergoing chemotherapy for relapsed follicular lymphoma. Her complex medical background included chronic kidney disease, heart failure, and recent skin infections. She presented with severe pain and swelling in a surgically replaced right knee. Initial evaluations, complicated by neutropenia and a necrotic lung lesion, suggested atypical infections. Despite broad-spectrum antibiotic therapy, the infection persisted. Synovial fluid analysis confirmed N.cyriacigeorgica, prompting surgical debridement and a modified antibiotic regimen. However, resistance issues and severe side effects complicated treatment, leading to a progressive decline in her condition. This case underscores the challenges of diagnosing and treating N.cyriacigeorgica infections, highlighting the need for enhanced diagnostic methods and personalized treatment approaches to manage resistance and complex patient profiles effectively.