Nocardia Osteomyelitis in Humans-A Narrative Review of Reported Cases, Microbiology, and Management.

Nocardiosis is an infection caused by Gram-positive, saprophytic bacteria most often affecting immunocompromised hosts. The lungs, central nervous system, and skin are the sites most typically involved, although any organ may be affected. Skeletal involvement, particularly osteomyelitis, remains uncommon. This study is a review of all published cases of Nocardia osteomyelitis in humans, emphasizing epidemiology, microbiology, clinical features, management, and patient outcomes. A narrative review was performed using data from the PubMed/MedLine and Scopus databases. Fifty studies describing 55 patients were included. The median age was 54 years, and 65.5% were male. The main risk factors were immunosuppression (21.8%) and trauma (18.2%). The vertebrae constituted the most commonly affected site (25.5%), followed by the lower limb bones (20%); 23.6% had multifocal disease. Nocardia asteroides accounted for the majority of cases (34.8%). Trimethoprim-sulfamethoxazole was the most frequently administered agent (81.5%), followed by cephalosporins (29.6%) and carbapenems (27.8%). Overall mortality was 9.3%, with 5.6% of reported deaths directly attributed to the infection. Although uncommon, osteomyelitis due to Nocardia spp. should be considered when Gram-positive, filamentous microorganisms are detected in bone specimens, particularly in immunocompromised or post-trauma patients, as early suspicion and targeted therapy may improve survival.