Musculoskeletal infections associated with Nocardia species: a case series

Background: Nocardia is an uncommon pathogen that has been reported to infect musculoskeletal structures. However, studies are largely limited to case reports, and little is known regarding management and outcomes of these infections. Methods: We performed a multicenter retrospective cohort study of adults with culture-confirmed musculoskeletal Nocardia infections at three Mayo Clinic centers in Arizona, Florida, and Minnesota from November 2011 through April 2022. Results: Nine cases of Nocardia musculoskeletal infection were identified. Seven (78 %) occurred in men, and the median age was 57.3 years (range 32.6-79.0). Specific infections included native joint septic arthritis with or without associated osteomyelitis ( $N=3$ ), hardware-associated infection ( $N=1$ ), sternal osteomyelitis ( $N=1$ ), pyomyositis ( $N=2$ ), bursitis ( $N=1$ ), and tenosynovitis ( $N=1$ ). Three cases (33 %) were associated with disseminated disease, all three occurring in solid organ transplant recipients. Surgical intervention was performed in all but the bursitis case. Length of treatment varied from 21 d for tenosynovitis to 467 d for osteomyelitis. The 1-year mortality was 22 %, and all fatal cases involved disseminated disease. Fazit: Patients with localized nocardiosis affecting musculoskeletal structures generally have good outcomes, as opposed to those with disseminated infection. Management often required operative intervention, with one patient experiencing recurrence within 1 year.