Nocardia Infections in Hematopoietic Cell Transplant Recipients: A Multicenter International Retrospective Study of the Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

Background Nocardiosis is rare after hematopoietic cell transplantation (HCT). Little is known regarding its presentation, management, and outcome in this population. Methods This retrospective international study reviewed nocardiosis episodes in HCT recipients (1/1/2000–31/12/2018; 135 transplant centers; 33 countries) and described their clinical, microbiological, radiological, and outcome characteristics. Results We identified 81 nocardiosis episodes in 74 allo- and 7 auto-HCT recipients. Nocardiosis occurred a median of 8 (IQR: 4–18) months post-HCT. The most frequently involved organs were lungs (70/81; 86%) and brain (30/81; 37%); 29 (36%) patients were afebrile; 46/81 (57%) had disseminated infections. The most common lung imaging findings were consolidations (33/68; 49%) or nodules (32/68; 47%); brain imaging findings were multiple brain abscesses (19/30; 63%). Ten of 30 (33%) patients with brain involvement lacked neurological symptoms. Fourteen of 48 (29%) patients were bacteremic. Nocardia farcinica was the most common among molecularly identified species (27%; 12/44). Highest susceptibility rates were reported to linezolid (45/45; 100%), amikacin (56/57; 98%), trimethoprim-sulfamethoxazole (57/63; 90%), and imipenem (49/57; 86%). One-year and last follow-up (IQR: 4–42.5 months) all-cause mortality were 40% (32/81) and 52% (42/81), respectively. In the multivariable analysis, underlying disease not in complete remission (HR: 2.81; 95% CI: 1.32–5.95) and prior bacterial infection (HR: 3.42; 95% CI: 1.62–7.22) were associated with higher 1-year all-cause mortality. Conclusions Nocardiosis is a late post-HCT infection usually manifesting as a pulmonary disease with frequent dissemination, brain infection, and bacteremia. Brain imaging should be performed in HCT recipients with nocardiosis regardless of neurological symptoms. Overall mortality is high.