Risk factors for mortality after nocardiosis in Southern France (2014-2024)

To analyze the risk factors associated with 1-year overall mortality in patients with nocardiosis.

This retrospective multicenter study was conducted across four university hospitals within the same health care network over 11 years (2014-2024) in Marseille, France. Age-adjusted exact multivariable logistic regression was performed to identify factors associated with 1-year overall mortality.

Of the 78 patients with a positive Nocardia spp. sample, 52 (66.7%) had a confirmed infection. Of these patients, 53.8% (28/52) had advanced forms, 34.6% (18/52) had disseminated forms, and 65.4% (34/52) had localized forms. The 1-year mortality rate was 21.2% (11/52), reaching 37.5% (six of 16) in the transplant subgroup and 32.1% (nine of 28) in patients with an advanced form. Severe lymphopenia (<0.5 G/l) was independently associated with 1-year mortality (odds ratio 5.70; 95% confidence interval 1.15-35.23). The main species identified was Nocardia abscessus (16/48, 33%), followed by Nocardia farcinica (9/48, 19%). Neither species was associated with an increased risk of 1-year mortality. All isolates except one were susceptible to imipenem (98%). Ninety-seven percent were susceptible to amikacin, 96.5% to linezolid, and 79% to trimethoprim-sulfamethoxazole. Mortality did not differ according to the adequacy of initial antibiotic therapy, based on antibiotic susceptibility testing or reference charts.

Solid organ transplantation and advanced disease were associated with higher crude 1-year mortality rates. In the age-adjusted multivariable analysis, severe lymphopenia (<0.5 G/l) was the only factor independently associated with 1-year mortality.