Abstract
Mycoplasma pneumoniae typically causes mild respiratory infections but can rarely lead to severe complications. We report a case of a 43-year-old immunocompetent male who presented with progressive dyspnea and respiratory failure with bilateral pulmonary infiltrates, refractory to outpatient treatment with azithromycin, ceftriaxone, and levofloxacin. Bronchoscopy revealed multiple white plaques in the trachea and diffuse alveolar hemorrhage. Although initial throat loop-mediated isothermal amplification (LAMP) testing for M. pneumoniae was negative, FilmArray analysis of bronchoalveolar lavage fluid successfully detected M. pneumoniae. The patient improved with minocycline and methylprednisolone treatment. This case demonstrates that M. pneumoniae can cause severe complications, including diffuse alveolar hemorrhage, even in immunocompetent patients. In some cases, it highlights the importance of lower respiratory tract sampling for accurate diagnosis.