Clinical Differences between Community-Acquired Mycoplasma pneumoniae Pneumonia and COVID-19 Pneumonia.

Mycoplasmapneumoniae is one of the major causative pathogens of community-acquired pneumonia (CAP). M. pneumoniae CAP is clinically and radiologically distinct from bacterial CAPs. One feature of the Japanese Respiratory Society (JRS) guidelines is a trial to be carried out to differentiate between M. pneumoniae pneumonia and bacterial pneumonia for the selection of antibiotics. The purpose of the present study was to clarify the clinical and radiological differences of the M. pneumoniae CAP and coronavirus disease 2019 (COVID-19) CAP. This study was conducted at 5 institutions and assessed a total of 210 patients with M. pneumoniae CAP and 956 patients with COVID-19 CAP. The median age was significantly younger in patients with M. pneumoniae CAP than COVID-19 CAP. Among the clinical symptoms, cough and sputum were observed more frequently in patients with M. pneumoniae CAP than those with COVID-19 CAP. However, the diagnostic specificity of these findings was low. In contrast, loss of taste and anosmia were observed in patients with COVID-19 CAP but not observed in those with M. pneumoniae CAP. Bronchial wall thickening and nodules (tree-in-bud and centrilobular), which are chest computed tomography (CT) features of M. pneumoniae CAP, were rarely observed in patients with COVID-19 CAP. Our results demonstrated that there were two specific differences between M. pneumoniae CAP and COVID-19 CAP: (1) the presence of loss of taste and/or anosmia and (2) chest CT findings.