Case Report: A case of Nocardia otitidiscaviarum pneumonia diagnosed by application of metagenome next-generation sequencing and a narrow literature review.

Nocardia is an opportunistic pathogen with relatively low incidence but high mortality. Recently, reports of Nocardia infections have increased; however, infections caused by Nocardia otitidiscaviarum (N. otitidiscaviarum) remain relatively rare. Due to its non-specific clinical manifestations and imaging features, N. ototidiscaviarum infections are frequently misdiagnosed or underdiagnosed, and no standardized guidelines currently exist for their diagnosis and treatment. In this study, we report a case of pulmonary infection caused by N. otitidiscaviarum, which was diagnosed using a combination of traditional microbial morphology and second-generation sequencing, and subsequently showed improvement following treatment with trimethoprim-sulfamethoxazole (TMP-SMZ) and linezolid. Additionally, we conducted a comprehensive literature review using PubMed to provide insights for improving the diagnosis and treatment of N. otitidiscaviarum infections.