Pseudomonas aeruginosa evolution in an 83-year-old male patient

In recent years, with the increasing global antimicrobial resistance, phage therapy has emerged as one of the most promising alternatives to antibiotics. Numerous studies have reported the effectiveness and safety of phage therapy in treating multidrug-resistant bacterial infections. However, there is limited research on the relationship between the emergence of phage-resistant strains and clinical outcomes. In this study, we applied phage nebulization therapy to a patient with carbapenem-resistant Pseudomonas aeruginosa lung infection. After 8 weeks of treatment with P. aeruginosa phages, the patient's sputum bacterial load decreased, overall inflammatory markers decreased, and lung effusion significantly reduced. During the treatment, a phage-resistant P. aeruginosa strain NPA13B was isolated. To investigate the relationship between the emergence of phage-resistant strains and clinical outcomes, we performed whole-genome sequencing analysis on the resistant strain and validated the effect of phage resistance on bacterial virulence using the Galleria mellonella larvae infection model. Our conclusion is that phage therapy against P. aeruginosa demonstrates positive effects in reducing the bacterial load and improving clinical symptoms in the lungs.