ABSTRACT
Introduction: Mycobacterium mucogenicum belongs to the rapidly growing mycobacteria, and it is a rare conditional pathogen. Although recent studies suggested that the incidence of M. mucogenicum infection was increased worldwide, there are no case reports of M. mucogenicum and Klebsiella pneumoniae pulmonary infection. Case Presentation: A 32-year-old non-smoking male was diagnosed with congenital atrial septal defect and pulmonary arterial hypertension. After cardiac surgery, lung infections were observed in the patient and then rapidly developed acute respiratory distress syndrome. The cefoperazone and sulbactam, vancomycin, ceftazidime, carbapenem, tigecycline, and micafungin were used for the treatment of pulmonary infection but did not affect. Ultimately, M. mucogenicum and K. pneumoniae were identified as pathogens by using next-generation sequencing. The patient was treated successfully with the administration of clarithromycin, linezolid, tigecycline, and ceftazidime-avibactam. The clinical outcome of this patient was favorable without relapse of infection. Conclusions: This case demonstrates that M. mucogenicum pulmonary infection may result in severe outcomes. The next-generation sequencing technology is important for the identification of M. mucogenicum. Additionally, the clinicians and clinical pharmacists should remain awareness in dealing with M. mucogenicum infection to avoid delaying appropriate treatment.