Hypersensitivity pneumonitis due to unclean continuous positive airway pressure equipment

Pneumocystis jirovecii pneumonia presenting as a solitary pulmonary granuloma due to unclean continuous positive airway pressure equipment: a case report

Continuous positive airway pressure (CPAP) therapy can spread infections if the equipment is not cleaned properly. We report a case of Pneumocystis jirovecii pneumonia likely spread by unclean CPAP equipment and accessories. A 48-year-old man with severe obstructive sleep apnea was using CPAP equipment that had never been cleaned for 5 years. He experienced intermittent mild fever for 6 weeks. His chest images showed a solitary pulmonary granuloma. Pneumocystis jirovecii was identified from the bronchoalveolar fluid, the CPAP mask, and the air tubing. The fever subsided immediately after changing to a clean CPAP device. We prescribed sulfamethoxazole 400 mg and trimethoprim 80 mg twice daily for one month. Three months later, the pulmonary granuloma disappeared, and Pneumocystis jirovecii was absent in the bronchoalveolar fluid. Poorly cleaned CPAP devices could harbor Pneumocystis jirovecii and spread pulmonary infection in immunocompetent persons. Appropriate cleaning of CPAP equipment is essential to minimize infection risk.

The hidden history of hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a relatively new construct, first reported in the early 20th century, despite major aetiologic factors (farming, bird husbandry) being part of human activities for millennia. Initial confirmed HP reports include exposure to farming and forestry (1932) and bird exposure (1965), much more recently in time than is often assumed. Later changes in occupational and living practices have led to HP associated with isocyanates, machine coolants, indoor mould, hot tubs, and other exposures. Evolution in our pathological understanding of interstitial lung disease in general, wider computerised tomography (CT) utilisation, and advances in immunology and genomics have shaped our modern conceptualisation of HP. Examining historical accounts of HP and its causative factors not only considers when the first cases were recognised, but also explores why the disease emerged at specific times and places, and may provide further insights relevant to the mechanisms underlying HP and disease prevention.