Letter to the Editor: Evidence for a two-step species-level pulmonary nocardiosis diagnostic approach.

Pulmonary nocardiosis, a rare and diagnostically challenging infection, usually presents with heterogeneous radiographic findings, compounded by the low sensitivity of traditional confirmatory cultures. In their most recent work, Wang et al analyzed 102 patients with pulmonary nocardiosis to address these concerns, investigating species-characteristic imaging patterns, pathological associations, and the role of metagenomic next-generation sequencing (mNGS) in the diagnostic approach. High-resolution computed tomography (CT) in adult patients with pulmonary infections caused by Nocardia wallacei was demonstrated to have a sensitive (85.71%) and specific (83.34%) presentation of bronchopneumonia in relation to the five Nocardia species in the sample with CT data. The authors also compared traditional cultures to mNGS, finding that traditional cultures and mNGS were concordantly positive in only 3.3% of cases. This letter supports a combined radiologic and molecular diagnostic approach, enabling earlier and more accurate species identification in pulmonary nocardiosis, thereby informing treatment decisions, and enhancing epidemiologic understanding.