Pertussis is identified among common respiratory diseases: A case report.

Pertussis, caused by Bordetella pertussis, is increasingly recognized in adults who often present with atypical symptoms, leading to underdiagnosis. We report a case of a 64-year-old woman with a persistent cough and sore throat initially treated as refractory community-acquired pneumonia. Despite empirical antibiotic therapy, her symptoms persisted. Conventional diagnostic tests, including sputum and bronchoalveolar lavage fluid cultures, were negative. Metagenomic next-generation sequencing of bronchoalveolar lavage fluid identified Bordetella pertussis with high sequence coverage (7497 reads). The patient showed no clinical improvement with azithromycin, prompting a switch to trimethoprim-sulfamethoxazole, after which she improved and was discharged to complete a 14-day course. At 1-month follow-up, she was asymptomatic with resolved radiographic findings. This case highlights that pertussis can mimic refractory pneumonia in adults without typical features such as whooping cough, and underscores the diagnostic value of metagenomic next-generation sequencing when conventional methods fail. Clinicians should consider pertussis in adults with prolonged cough unresponsive to standard community-acquired pneumonia therapy and be aware of potential macrolide resistance, which may necessitate alternative antibiotics like trimethoprim-sulfamethoxazole.