Isolation and Characterization of Pseudomonas aeruginosa Phages with a Broad Host Spectrum from Hospital Sewage Systems and Their Therapeutic Effect in a Mouse Model.

ABSTRACT

This study aimed to isolate and characterize phages as an alternative treatment of multidrug- or pan-drug-resistant Pseudomonas aeruginosa. Phage titers and bacterial densities correlated, with the phages disappearing after bacteria were eliminated. We isolated phages in filtered sewage water by a double-layered agar spot test. Fifty-eight P. aeruginosa strains were used to screen the host spectrum of the 14 phages isolated. Random amplification of polymorphic DNA-typing polymerase chain reaction was used to analyze the genomic homologies of the 58 host bacteria strains and four phages with a broad host spectrum. Transmission electron microscopy was used to observe the morphology of the four phages with a broad host spectrum. Mice with intraabdominal P. aeruginosa infection were used as an in vivo animal model to investigate the therapeutic effect of the selected phage. Four virulent phages with a broad host spectrum specific to P. aeruginosa strains were isolated. They were all double-stranded DNA viruses and belonged to four different genotypes. The test curve showed that phage I had the highest adsorption rate, the shortest latent period, and the largest burst size. The infected mouse model indicated that small doses of phage I could prevent the death of infected mice. Phage titers and bacterial densities correlated, with phages disappearing after bacteria were eliminated. Phage I was the most effective and promising treatment of drug-resistant P. aeruginosa.