Respiratory infection of cyclophosphamide-treated mice with Pseudomonas aeruginosa

The dose of cyclophosphamide that permits the colonization of the nasopharynx with Pseudomonas aeruginosa and the survival of the animal was determined in mice. This dose, 100 mg/kg of cyclophosphamide, allowed P aeruginosa to colonize but not invade mouse nasal epithelium. Mice treated with 100 mg/kg cyclophosphamide were exposed to aerosol of 35S-labeled P aeruginosa to study clearance. Results indicated that this dose of cyclophosphamide suppressed both the pulmonary clearance of viable P aeruginosa (in situ killing) and the clearance of radiolabeled P aeruginosa (mechanical clearance).