Shorter vs. standard-duration antibiotic therapy for nocardiosis: a multi-center retrospective cohort study

Abstract

Purpose: The prolonged treatment recommended for nocardiosis does not rely on strong evidence. Consequently, some clinicians opt shorter therapy in certain circumstances. We assessed the effectiveness of shorter therapy.

Methods: A multi-center retrospective cohort study comprising individuals diagnosed with nocardiosis between 2007 and 2022. We classified all patients who survived 90 days into three groups according to treatment duration: short (≤ 90 days), intermediate (91-180 days), and prolonged (> 180 days). We compared baseline characteristics (comorbidities, immune status) and nocardiosis manifestations across the unadjusted treatment groups, one-year all-cause mortality, disease relapse, and antibiotic-related adverse events to identify patients who may safely receive the short course.

Results: We detected 176 patients with nocardiosis, their median age was 65 years; 74 (42%) were women. Forty-three (24%) patients died within 90 days. Of the remaining 133, 37 (28%) patients received short therapy, 40 (30%) intermediate, and 56 (42%) prolonged treatment duration. Longer courses were more likely to be administered to patients with immunosuppression, disseminated nocardiosis, and N. farcinica infection. Within a year, 20 (15%) individuals died and 2 (2%) relapsed. Treatment duration was not associated with either mortality (p = 0.945) or relapse (p = 0.509). Nocardiosis was the cause of death in only one patient, receiving a prolonged course. Of 73 patients with solitary pulmonary nocardiosis, 20 (27%) received short duration. None relapsed and 2 (10%) died, both immunocompromised. The rate of AE was similar across the groups.

Conclusions: With clinically guided case-by-case patient selection nocardiosis can be safely treated for durations significantly shorter than traditionally recommended.

Keywords: Immune suppression; Nocardia; Opportunistic infections; Treatment.

Fig. 1

Study flow diagram

Fig. 2

Distribution of treatment duration groups according to nocardiosis clinical syndrome and immune status. For each treatment duration group (represented by colors), the shades signify the immune status (apparent immunocompetence, and mild-moderate or substantial immune suppression): the darker the shade the diminished the immunity

Fig. 3

Survival curves of the cohort, according to the treatment group. The entire cohort is presented as a single curve up to 90 days, then divided into 3 treatment groups, according to the total treatment duration. p value calculated using Log-rank test