ACTIVITY OF AZTREONAM IN PNEUMOLOGY .2. INFLUENCE ON PHAGOCYTOSIS AND INTRACELLULAR KILLING OF HUMAN ALVEOLAR MACROPHAGES

The study aim was to evaluate the activity of aztreonam on phagocytosis and intracellular killing of Staphylococcus aureus ATCC6538 by human alveolar macrophages. Drug concentrations of 1, 10, 25, 100 mu g/ml were assayed in culture medium. Aztreonam induces dose-dependent phagocytosis up to 25 mu g/ml concentrations; with a phagocytosis index (PIa) of 1.18 +/- 0.2 at 1 mu g/ml; of 1.27 +/- 0.2 at 10 mu g/ml; of 1.42 +/- 0.3 at 25 mu g/ml. No phagocytosis increase or inhibition, with unchanged cell viability compared to controls, is shown at 100 mu g/ml aztreonam (PI 1.03) +/- O.3). Intracellular killing acts in a similar way: the killing index (KIa) is 1.27 +/- 0.3) at 1 mu g/ml concentrations; 1.38 +/- 0.3 at 10 mu g/ml; 1.61 +/- 0.4 at 25 mu g/ml whereas at 100 mu g/ml the KIa is 1.03 +/- 0.3. This study shows aztreonam's ability to stimulate macrophages' functional activity against a microorganism (S. aureus) which is not susceptible to its antibacterial activity.