Metagenomic next-generation sequencing for diagnosis of severe pneumonia caused by Nocardia otitidiscaviarum.

Introduction: Nocardia spp. are Gram-positive, aerobic actinomycetes, which can cause pulmonary, primary cutaneous, and lymphocutaneous infections. However, severe pneumonia caused by Nocardia otitidiscaviarum has rare reported.

Patient concerns: In this case report, a 73-year-old female presented with a 7-day history of fever, cough, followed by a 1-day history of dyspnea. Both lungs showed patchy shadows on a chest CT scan. Bronchoalveolar lavage and mNGS were performed for the rapid diagnosis of the Nocardia otitidiscaviarum induced infection.

Diagnosis: Community-acquired pneumonia was diagnosed following clinical assessment, including characteristic physical examination findings, abnormal laboratory results, and consolidations observed on CT imaging. And the evidence of pathogen was supplied by mNGS.

Interventions: The anti-infection therapy regimen was: trimethoprim-sulfamethoxazole (1.44 g q6h) for 3 months according to the detection of the Nocardia otitidiscaviarum.

Outcomes: After 3 months of follow-up, the patient has a good outcome and chest CT suggested that the inflammation in the lungs had been almost absorbed.

Conclusions: Rapid pathogen identification is pivotal for enhancing clinical outcomes and survival in severe pneumonia patients. This case report presents an exceptional case of severe pneumonia caused by Nocardia otitidiscaviarum and the uncommon potential occurrence of human-to-human transmission. mNGS could help avoid misdiagnosis and mistreatment in clinical practice.