Metagenomic next-generation sequencing in the diagnosis of leptospirosis presenting as severe diffuse alveolar hemorrhage: a case report and literature review.

Background: Leptospirosis is a common infectious disease in tropical and semitropical regions, and it is typically neglected. Leptospirosis-associated acute diffuse alveolar hemorrhage is one of its fatal complications. The use of bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing in the diagnosis of Leptospira interrogans infection has rarely been reported.

Case Presentation: We present the case of a 62-year-old female who was transferred to our hospital with dyspnea, and severe hemoptysis and was supported by a tracheal intubation ventilator. Bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing (mNGS) reported Leptospira interrogans. A diagnosis of diffuse alveolar hemorrhage caused by leptospirosis was made. After immediately receiving antibiotics and hormone therapy, the patient achieved a complete recovery upon discharge.

Conclusion: Leptospirosis presenting as severe diffuse alveolar hemorrhage is rare but should be considered in the differential diagnosis. mNGS can help identify pathogens and treat them early, which can improve prognosis.