Non-serogroupable pneumonia in an immunocompetent patient with severe COVID-19 pneumonia: A case report.

Background: Non-serogroupable () the most common type of in asymptomatic carriers, rarely causes infections. Most reported cases of infection are in patients with immunodeficiency, primarily complement deficiencies.

Case Presentation: A 54-year-old immunocompetent man was transferred to our hospital to treat severe coronavirus disease 2019 (COVID-19). The patient presented with cough producing a large amount of purulent sputum, which was considered an atypical presentation of COVID-19. Gram staining of the sputum revealed a large number of gram-negative diplococci phagocytosed by many neutrophils, and a diagnosis of bacterial pneumonia was established. The culture yielded non-serogroupable and the patient was diagnosed with non-serogroupable pneumonia. Potential immunodeficiency was considered; however, testing including human immunodeficiency virus and complement factors showed no abnormalities.

Conclusions: We report herein a rare case of non-serogroupable pneumonia that occurred in an immunocompetent patient during the course of severe COVID-19. We consider impaired T cell function attributable to COVID-19 and dexamethasone administration may have triggered a transient immunosuppressive state and led to non-serogroupable pneumonia.