Characterization and therapeutic potential of vB_PaeM_QR7: a highly efficient lytic bacteriophage against multidrug-resistant Pseudomonas aeruginosa

AIMS: The increasing burden of multidrug-resistant (MDR) Pseudomonas aeruginosa (P. aeruginosa) infections highlights the need for antibiotic-sparing approaches. This study isolated and characterized a lytic bacteriophage active against MDR P. aeruginosa and evaluated its potential for infection control and milk decontamination. METHODS AND RESULTS: The lytic bacteriophage vB_PaeM_QR7 was isolated from sewage and characterized using morphological, phenotypic, and genomic analyses. Whole-genome sequencing revealed a 45 421-bp linear double-stranded DNA genome with no predicted virulence determinants and antibiotic resistance genes. vB_PaeM_QR7 showed high lytic efficiency (optimal MOI = 1 × 10-5), stability across 30-50°C and pH 4-11, a short latent period, and a burst size of 92.43 ± 52.29 PFU cell-1. The bacteriophage inhibited biofilm formation by 65.88 ± 0.04% and reduced established biofilms by 71.27 ± 0.05%. In milk, vB_PaeM_QR7 reduced bacterial loads by 5.40 ± 0.12 log10 CFU mL-1 , and in the Galleria mellonella infection model, it increased larval survival by 50%. CONCLUSIONS: vB_PaeM_QR7 is a newly identified lytic bacteriophage with activity against 10 MDR P. aeruginosa isolates, including cephalosporin- and carbapenem-resistant strains, supporting its further development as an alternative antimicrobial agent.