Nocardia infection in patients with anti-GM-CSF autoantibodies: a prospective multicenter French study

Abstract Background Nocardiosis, a bacterial opportunistic infection caused by Nocardia spp., has recently been reported in patients with anti-Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF) autoantibodies but insufficient data are available about disease presentation, outcomes, and occurrence of autoimmune pulmonary alveolar proteinosis (aPAP) in this population. Methods We performed a prospective, multicenter, nationwide study in France and included patients with a Nocardia infection who had anti-GM-CSF autoantibodies. We describe their clinical, microbiological, and radiological characteristics, and their outcome at 1 year of follow-up. Results Twenty patients were included, 18 (90%) men, median age 69 [44-75] years. The organs most frequently involved were the brain (14/20; 70%) and the lung (12/20; 60%). Half of the infections were disseminated (10/20; 50%). Nocardia identification was predominantly made in abscess fluid (17/20; 85%) among which 10 (59%) were brain abscesses. The one-year all-cause mortality was 5% (1/20) and only one case of aPAP (1/20; 5%) occurred during the follow-up period. Conclusions Nocardiosis with anti-GM-CSF autoantibodies is associated with a low mortality rate despite a high incidence of brain involvement. Although the occurrence of aPAP was infrequent during the one-year follow-up period, long-term clinical data are needed to fully understand the potential relationship between nocardiosis, anti-GM-CSF autoantibodies, and aPAP.