A case of lower respiratory tract infection caused by Pandoraea sputorum in a human T-lymphotropic virus type 1 carrier.

Pandoraea sputorum is a rare, multidrug-resistant, non-fermenting Gram-negative bacillus that has emerged as an opportunistic pathogen, particularly in patients with cystic fibrosis (CF). Reports of infections in individuals without CF remain limited. We report a case of a lower respiratory tract infection caused by Pandoraea sputorum in an individual without CF. A 66-year-old Japanese man with a history of right upper lobectomy for large cell carcinoma 10 years ago and human T-lymphotropic virus type 1 (HTLV-1) carrier status presented with recurrent hemoptysis and impaired pulmonary function. Imaging revealed centrilobular nodules and bronchial wall thickening. Stenotrophomonas maltophilia was initially isolated from the bronchial washing fluid; however, its susceptibility to imipenem raised concerns about potential misidentification. Subsequently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry confirmed the pathogen as Pandoraea sputorum. The patient was successfully treated with a combination of imipenem/cilastatin, trimethoprim-sulfamethoxazole, and minocycline, resulting in the resolution of symptoms, and radiological and functional improvement were confirmed. This case highlights the challenges of identifying Pandoraea species using conventional biochemical methods, suggesting the potential underestimation of this pathogen in individuals without CF. It also suggests that although HTLV-1 carriers are generally considered immunocompetent, they exhibit subtle immune dysregulation that predisposes them to opportunistic infections. Therefore, clinicians should consider opportunistic infections, including those caused by Pandoraea species, in individuals without CF who have underlying structural lung disease or potential immune modulation, and utilize advanced diagnostic techniques to ensure accurate identification and appropriate treatment.