Effects of respiratory tract infections and antibiotic therapy on NADPH oxidase activity]

The superoxide generation of neutrophil NADPH oxidase was investigated in healthy subjects, patients with respiratory tract infections, and patients receiving effective antibiotic therapy. In adults, oxidase activity significantly increased during respiratory tract infections and decreased after treatment with effective antibiotics. In the elderly, no significant increase in oxidase activity was observed during respiratory tract infections, while the activity significantly decreased after therapy. Increases in white blood cell counts, neutrophil counts and C-reactive protein values in the elderly during respiratory tract infections were less marked than those in adults. These abnormalities in both adults and the elderly were restored to within normal limits after antibiotic therapy. In in vitro experiments, antibiotics, such as imipenem, ceftazidime and cefoperazone, at each therapeutic dose did not inhibit the superoxide generation of NADPH oxidase. These results suggest that in the elderly, defense activity against infections may be suppressed, and that these antibiotics may normalize neutrophil NADPH oxidase activity as a result of their bactericidal action and a possible biological action to normalize the peri-neutrophil environment of the body.