Staphylococcus aureus (SA – Newman) and Pseudomonas aeruginosa (PA14) reference strains were used to establish chronic co-infection in C57Bl/6NCr mice. Different protocols of amoxicillin/clavulanate (AC) administration were tested in mice infected by SA. After SA infection and antibiotic treatment mice were infected by Pa. Mice were monitored for body weight, mortality and lungs were processed for bacterial count, inflammatory response and histological analysis.
Treatment with 200 mg/Kg of AC was effective in containing SA infection with a decrease of SA bacterial load and inflammatory response up to 26 days from infection. However, both infection and inflammation were not completely resolved in this model. The capacity of SA pre-infection to increase Pa colonization was not affected by anti-SA treatment in murine lungs. Histopathology revealed that the antibiotic did not resolve completely the lung damage that was worsen by the Pa infection able to increase leukocytes recruitment at both bronchial and parenchymal levels.