Modern antibiotic therapy of respiratory infections is based on clinical trials and multicentre analyses. The recommendations that have been made take into account the available antibiotics and their microbiological efficacy. The choice of antibiotic should also take into account its pharmacokinetic characteristics, including the minimum inhibitory concentration and the degree of penetration into the airways and pulmonary parenchyma. Significant differences in this area clearly indicate the reasonableness of the choice made, which translates into the effectiveness of the treatment. Because more and more often the cause of respiratory infections are atypical bacteria, an important feature of the administered antibiotic is its ability to penetrate inside the cell, where these bacteria multiply. In turn, the ability of some bacteria, e.g. Pseudomonas aeruginosa, to biofilm to a large extent hinders the treatment process, because most antibiotics do not have the ability to penetrate this structure. The above premises indicate the predominance of macrolides and fluoroquinolones in controlling the infection in the respiratory system. The treatment of patients with symptoms of respiratory infections by inhaled administration of azithromycin in the form of microparticles proved to be effective in comparison to other conventional therapies.