Bacteriophages ϕMR299-2 and ϕNH-4 Can Eliminate Pseudomonas aeruginosa in the Murine Lung and on Cystic Fibrosis Lung Airway Cells
ABSTRACTPseudomonas aeruginosais a common cause of infection in the lungs of patients with cystic fibrosis (CF). In addition, biofilm formation and antibiotic resistance ofPseudomonasare major problems that can complicate antibiotic therapy. We evaluated the efficacy of using bacteriophages to kill the pathogen in both biofilms and in the murine lung. We isolated and characterized two phages from a local wastewater treatment plant, a myovirus (ϕNH-4) and a podovirus (ϕMR299-2). Both phages were active against clinical isolates ofP. aeruginosa. Together, the two phages killed all 9 clinical isolate strains tested, including both mucoid and nonmucoid strains. An equal mixture of the two phages was effective in killingP. aeruginosaNH57388A (mucoid) andP. aeruginosaMR299 (nonmucoid) strains when growing as a biofilm on a cystic fibrosis bronchial epithelial CFBE41o- cell line. Phage titers increased almost 100-fold over a 24-h period, confirming replication of the phage. Furthermore, the phage mix was also effective in killing the pathogen in murine lungs containing 1 × 107to 2 × 107P. aeruginosa.Pseudomonaswas effectively cleared (reduced by a magnitude of at least 3 to 4 log units) from murine lungs in 6 h. Our study demonstrates the efficacy of these two phages in killing clinicalPseudomonasisolates in the murine lung or as a biofilm on a pulmonary cell line and supports the growing interest in using phage therapy for the control and treatment of multidrug-resistantPseudomonaslung infections in CF patients.IMPORTANCEGiven the rise in antibiotic resistance, nonantibiotic therapies are required for the treatment of infection. This is particularly true for the treatment ofPseudomonasinfection in patients with cystic fibrosis. We have identified two bacterial viruses (bacteriophages) that can killPseudomonasgrowing on human lung cells and in an animal model of lung infection. The use of bacteriophages is particularly appropriate because the killing agent can replicate on the target cell, generating fresh copies of the bacteriophage. Thus, in the presence of a target, the killing agent multiplies. By using two bacteriophages we can reduce the risk of resistant colonies developing at the site of infection. Bacteriophage therapy is an exciting field, and this study represents an important demonstration of efficacy in validated infection models.