Refractory flare-up of severe bronchial asthma controlled with mepolizumab due to Pneumocystis pneumonia: a case report

BACKGROUND: Biologics dramatically improve symptoms of severe asthma; however, various exacerbating factors may induce flare-up. Pneumocystis spp. have not been reported as a cause of asthma exacerbation during biologic use, although patients with severe asthma have high levels of antibodies against Pneumocystis spp. CASE PRESENTATION: An 87-year-old female with severe asthma that was well-controlled with mepolizumab, who developed a steroid-resistant refractory flare-up. Chest computed tomography showed bilateral ground glass opacities, and results of polymerase chain reaction tests on induced sputum were positive for Pneumocystis DNA. Therefore, a diagnosis of Pneumocystis pneumonia was made. The clinical symptoms improved after treatment with sulfamethoxazole–trimethoprim. CONCLUSION: Clinicians should be aware of Pneumocystis pneumonia as a cause of refractory exacerbation of bronchial asthma during use of interleukin-5 inhibitors.