Among patients who develop nocardiosis following hematopoietic cell transplantation (HCT), brain imaging studies should be performed regardless of neurologic symptoms, according to results of a study published in Clinical Infectious Diseases.

A diagnosis of nocardiosis is rare following HCT, and little is known about its presentation, management, and associated outcomes. To address this knowledge gap, researchers performed a retrospective international study to evaluate nocardiosis episodes among patients who underwent HCT at 135 transplant centers in 33 countries between January 2000 and December 2018. The researchers assessed clinical, microbiologic, radiologic, and outcome characteristics among the included patients.

Among 74 patients who underwent allogenic-HCT and 7 who underwent autologous-HCT, 81 nocardiosis episodes were identified, occurring at a median of 8 (interquartile range [IQR], 4-18) months after HCT. The lungs (70/81; 86%) and brain (30/81; 37%) were the organs most frequently involved among patients who developed nocardiosis. In addition, most infections were disseminated (46/81; 57%) and 29 (36%) patients were afebrile.

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Imaging studies of the lungs showed that consolidations (33/68; 49%) or nodules (32/68; 47%) were the most common lesions. In addition, the most common finding on brain imaging studies were multiple brain abscesses among 19 patients (63%). Among 30 patients who developed nocardiosis with brain involvement, 10 (33%) lacked neurologic symptoms.

Blood cultures were collected from 48 patients, of whom 14 (29%) had Nocardia bacteremia on specimen analysis. Of note, N farcinica was the most common species identified. Antibiotic susceptibility testing found that susceptibility was most increased among patients treated with linezolid (45/45; 100%), followed by amikacin (56/57; 98%), trimethoprim-sulfamethoxazole (57/63; 90%), and imipenem (49/57; 86%). Data on antibiotic therapy was available for 80 patients, and the most frequently used antibiotics were trimethoprim-sulfamethoxazole (68%), imipenem (46%), and amikacin (44%).

At 1 year, all-cause mortality was 40% (32/81) and the median time to death was 2.5 (IQR, 1-6) months. Among all patients included in the study, the median duration of follow-up was 18 (IQR, 4-42.5) months. Of note, all-cause mortality was 52% (42/81) at the final follow-up visit. The researchers performed a multivariate analysis and found that the risk for all-cause mortality at 1 year was significantly increased among patients who were neither in continued nor complete remission of their underlying disease (hazard ratio [HR], 2.81; 95% CI, 1.32-5.95), as well as those with a prior bacterial infection (HR, 3.42; 95% CI, 1.62-7.22).

The study was limited by its retrospective design, heterogeneity among the treatment protocols, and the lack of available data on isolate susceptibility and therapy timing. In addition, there were insufficient data on species distribution.

According to the researchers, patients with nocardiosis post-HCT are at an overall increased risk of mortality. “Underlying disease status and concurrent infections appear to play key roles in the prognosis [of nocardiosis],” the researchers concluded.

Disclosure: Some author(s) declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Averbuch D, De Greef J, Duréault A, et al. Nocardia infections in hematopoietic cell transplant recipients: a multicenter international retrospective study of the Infectious Diseases Working Party (IDWP) of the European Society for Blood and Marrow Transplantation (EBMT). Clin Infect Dis. Published online October 1, 2021. doi:10.1093/cid/ciab866