Efficacy of Aerosolized Antibiotics in Acute and Chronic Pseudomonas Infection

Immunocompetent C57BL/6NCrlBR male mice (8–10 weeks; Charles River Laboratories, Calco, Italy) were challenged with 1×10⁶ colony-forming units (CFUs) of the planktonic PAO1 strain for acute infection or 5×10⁵ CFUs of the MDR-RP73 strain embedded in agar beads for chronic infection by intratracheal administration [12 (link)–14 (link)]. Mice were treated with TOB, COL or vehicle (water) by local administration using a Penn-Century MicroSprayer® Aerosoliser (aero) or by i.n. or systemic s.c. administration (figure 1). Body weight was monitored daily. Lung CFUs and cell counts in the bronchoalveolar lavage fluid (BALF) were analysed as described previously [13 (link), 18 (link), 19 (link)]. Cytokine/chemokine levels were measured in the supernatant of lung homogenates by Bioplex Assay (Bio-Rad Laboratories, Segrate, Italy). Pharmacokinetic (PK) profiles of TOB and COL in the lungs and plasma of P. aeruginosa-infected mice were evaluated by high-performance liquid chromatography–tandem mass spectrometry. Additional details in accordance with the Animal Research: Reporting of In Vivo Experiments guidelines [20 (link)] are reported in the supplementary material.