Bronchitis is an inflammation of the Bronchi's mucous membrane, characterized by coughing and excessive secretion of phlegm which partially occludes the respiratory tubes. The bronchi are the breathing branches into which the trachea divides. Bronchitis could be acute or chronic. The first type is more common in winter and usually follows an influenza virus infection. If not treated, and especially if the patient is undernourished, an intercurrent bacterial infection could occur that could develop into a pneumonia.