This PMOS will be conducted in a prospective, open-label, single-country, multicenter format. The investigational sites will be consulting rooms of GPs (general practitioner), pneumologists and centers with experience in the treatment of patients with lower respiratory tract infection, AECB (acute exacerbation of chronic bronchitis) and CAP (mild community-acquired pneumonia). Since this will be a PMOS, Klacid®SR will be prescribed in usual manner in accordance with the terms of the local market authorization with regards to dose, population and indication as well as local guidelines. The decision to prescribe or not prescribe Klacid®SR would be taken prior to entry of a subject in the study.