Azithromycin taken chronically for 1 year reduced the frequency of exacerbations of chronic obstructive pulmonary disease (COPD) as well as the incidence of colonization with respiratory pathogens but resulted in an increase in colonization with macrolide-resistant pathogens.
Source: Albert RK, Connett J, Bailey WC, et al. Azithromycin for prevention of exacerbations of COPD. N Engl J Med. 2011;365:689–698.