Redefining the diagnostic pathway for pulmonary nocardiosis: The imperative for early metagenomic sequencing

Abstract

In this article, we comment on the pivotal article by Wang et al. We focus on the critical intersection of advanced imaging and molecular diagnostics highlighted by their findings. The study delineates specific high-risk computed tomography patterns, notably consolidation with nodules/cavities, particularly in immunocompromised hosts or patients with bronchiectasis, that should serve as immediate red flags for pulmonary nocardiosis. Traditionally, diagnosis has relied on slow-growing cultures, leading to dangerous therapeutic delays. This editorial argues that the presence of these defined radiologic signatures may represent an important step toward refining the diagnostic pathway for pulmonary nocardiosis. Rather than a confirmatory last resort, metagenomic next-generation sequencing should be deployed as a first-line investigative tool following high-suspicion imaging. We propose a concrete, integrated diagnostic algorithm where imaging triage triggers parallel processing with metagenomic next-generation sequencing and conventional microbiology. This synergy of morphology and metagenomics promises to expedite species-specific diagnosis, guide timely targeted therapy, and ultimately improve outcomes for patients with this challenging and often elusive infection.

Keywords: Pulmonary nocardiosis; Metagenomic next-generation sequencing; Diagnostic algorithm; Computed tomography; Bronchiectasis; Immunosuppression

Core Tip: The large-scale study by Wang et al defines key computed tomography patterns that predict pulmonary nocardiosis. This article argues these imaging findings should trigger an immediate diagnostic shift, positioning metagenomic next-generation sequencing as a primary, not secondary, tool. A new algorithm integrating radiologic triage with rapid metagenomic next-generation sequencing testing can dramatically reduce diagnostic delay, enabling faster targeted treatment.