Saiki Yoshimura

1 Introduction Community-acquired pneumonia (CAP) is a common infectious disease, with an estimated annual incidence of approximately 1.88 million cases in Japan. The fatality rate of CAP remains approximately 2%–4%, and pneumonia accounts for the fourth leading cause of death in Japan. Streptococcus pneumoniae is the most frequently identified causative pathogen of CAP, followed by Haemophilus influenzae, Staphylococcus aureus, and Mycoplasma pneumoniae in Japan.

1 Introduction Coronavirus disease 2019 (COVID-19) is known to cause various respiratory sequelae even after the acute phase of pneumonia. One such sequela is bronchiectasis, with a higher risk observed especially in severe COVID-19 cases [1]. Bronchiectasis develops against a background of airway infection and inflammation, and bacterial colonisation is known to contribute to the worsening of the condition.