Activity of roxithromycin against respiratory pathogens.

The usefulness of macrolides in treating respiratory infections has been established for over thirty years. Currently, a great deal of interest is being focused on roxithromycin, a new semisynthetic derivative of erythromycin which is more stable than erythromycin under acidic conditions and exhibits improved pharmacokinetic properties. In this study, special attention is paid to the results of recent multicenter studies in Italy aimed at evaluating the in vitro activity of roxithromycin versus erythromycin against a wide range of respiratory pathogens. Considering that a high degree of overlap was observed between the roxithromycin-susceptible and the erythromycin-susceptible strains, whereas a significant proportion of erythromycin-resistant strains shifted to the intermediate category with roxithromycin, there appeared to be cross-susceptibility rather than cross-resistance between the two macrolides.