Considering the different epidemiology of the responsible pathogens in AECB, different classes of antibiotics appear appropriate in different GOLD severity classifications. For example, exacerbations in stages I and II patients can be treated in many countries, depending on local resistance, with macrolides, aminobenzylpenicillines, and newer cephalosporins. In more severe cases, fluoroquinolones and aminobenzylpenicillines together with β-lactamase inhibitors are more appropriate.