A polymicrobial opportunistic infection leading to osteolytic destruction and acute respiratory failure: a case report

Polymicrobial infections involving opportunistic pathogens pose major diagnostic challenges, as clinical symptoms and imaging findings are often nonspecific. Comprehensive pathogen identification is essential for effective management. This report describes a case of polymicrobial infection caused by Cryptococcus , Pseudomonas aeruginosa , Aspergillus , and Mycobacterium abscessus in a diabetic patient. A 67-year-old male presented with cough, sputum production, and bone pain. Chest computed tomography revealed a cavitary lesion in the posterior segment of the left lower lobe. Histopathology of lung biopsy confirmed pulmonary cryptococcosis. Respiratory symptoms initially improved with antifungal therapy, but bone pain persisted. After treatment discontinuation, symptoms recurred and worsened, accompanied by fever and respiratory failure. Sputum culture grew Pseudomonas aeruginosa , and next-generation sequencing of bronchoalveolar lavage fluid revealed concurrent infections with Mycobacterium abscessus and Aspergillus fumigatus . Ultimately, the patient recovered and was discharged after targeted therapy. This case underscores the inadequacy of single-pathogen frameworks in complex polymicrobial infections and highlights the clinical value of repeated assessment and a multimodal diagnostic approach. Early recognition of polymicrobial opportunistic infections may help prevent disease progression and improve clinical outcomes in susceptible patients.