Intracellular infections of the respiratory tract

Intracellular pathogens are phagocytosed microorganisms that retain their pathogenic activity. Thus, antimicrobial treatment must provide sufficient intracellular drug concentrations within the phagocyte to be effective. Respiratory tract infections, such as atypical pneumonias, can be a result of organisms capable of survival and reproduction even within alveolar macrophages; antimicrobial therapy should, therefore, consist of agents with the ability to accumulate intracellularly. Macrolides are effective treatment for atypical pneumonias in that they show excellent intracellular penetration. Among the macrolides, roxithromycin features a broad spectrum of activity and an improved pharmacokinetic profile compared with erythromycin. In addition, roxithromycin accumulates to a greater extent intracellularly and subcellularly than erythromycin. Thus, roxithromycin may provide an improved therapeutic outcome in the treatment of these infections