Pneumocystis jiroveci pneumonia, Nocardia brasiliensis, and Mycobacterium tuberculosis co-infection in a myasthenia gravis patient: A case report

RATIONALE: Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junctions that leads to fluctuating weakness and disabling fatigability. Due to difficulty in breathing caused by weakness of the respiratory muscles, patients with MG are more susceptible to pneumonia and other respiratory infections. As many patients with MG are given immunosuppressive therapy, this makes them more prone to infections. However, coinfection with 3 pathogens is very rare. PATIENT CONCERNS: Here, we report the case of a 41-year-old gentleman with MG who was receiving long-term steroid therapy. He presented with a cough with pale brown expectoration that occurred without obvious inducement, severe pain in the scapula, as well as swelling and weakness of both legs. Despite undergoing treatment, but his symptoms did not improve, prompting two additional hospital admissions over a period of several months. DIAGNOSIS: Bronchoscopy and bronchoalveolar lavage (BAL) were performed, revealing the presence of Pneumocystis jirovecii , Nocardia brasiliensis, and Mycobacterium tuberculosis (MTB). N brasiliensis was identified by positive modified acid-fast Kinyoun staining as well as a positive colony culture identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry from the BAL sample. MTB was confirmed using GeneXpert, and due to the limitations of the culture conditions, methenamine silver stain was used to confirm Pneumocystis jirovecii. Next-generation sequencing (NGS) assay of the BAL samples also confirmed these pathogens. INTERVENTIONS: The patient was transferred to a designated tuberculosis hospital and received anti-infective and anti-TB treatment. OUTCOMES: During treatment at the designated hospital, the patient developed gastrointestinal bleeding and impaired liver function. One month later, he developed multiple organ failure, consolidation of the left lower lung, and pan-drug resistant bacteremia. He refused further treatment and was discharged CONCLUSION: In conclusion, physicians should be aware of the predisposition of MG patients to co-infections, especially patients with metabolic disorders, to avoid inadequate treatment and poor patient outcomes. Due to the limitations of culture conditions, NGS should be considered as a new technique for identifying pathogens.