Among the other pathogens, Chlamydophila pneumoniae and Mycoplasma pneumoniae are currently drawing increasing consideration. They are frequent causes of community acquired pneumonia in children. Before the age of 10 years, almost 70% of children have had Chlamydophila pneumoniae infection based on serological studies [151] . These pathogens are intracellular organisms that primarily infect respiratory epithelial cells and alveolar macrophages and have the propensity to persist within several cell types such as macrophages. They are well known to cause a wide variety of respiratory manifestations, with possible progression towards diffuse parenchymal diseases associated with interstitial infiltrates on chest imaging and reduction in the lung diffusion capacity [152] . Regarding Legionella pneumophilia infection, progression towards ILD has been infrequently reported in adult patients.