Genomic characterization of a new member of the Phikmvvirus genus infecting multidrug-resistant high-risk clones of Pseudomonas aeruginosa.

The emergence and prevalence of antibiotic-resistant Pseudomonas aeruginosa strains have become a health priority, requiring novel treatment options. Among these, bacteriophages have regained attention in recent years due to their potential for combating bacterial infections and overcoming antibiotic resistance. Here, we present a new Phikmvvirus phage, with an icosahedral structure of 60-62 nm in diameter, which harbors a linear double-stranded DNA genome of 42,679 bp. The genome of Pseudomonas phage vB_Paphi_Mx1 contains 65 coding sequences (CDSs) related to nucleic acid metabolism, morphogenesis, packaging, and lysis. Thermostability ranges from 30 to 60 °C, and pH stability show that viral particles remain infective under pH 12. The phage vB_Paphi_Mx1 uses a holin-lysozyme-spanin system. Lytic activity against a panel of multidrug-resistant, extensively drug-resistant, pandrug-resistant, and carbapenemase-producing P. aeruginosa was 60.8 % (76/125), these include high-risk sequence types, some of which have caused pediatric deaths. Moreover, phage vB_Paphi_Mx1 reduced the biofilm biomass of biofilm-producing P. aeruginosa strains. To our knowledge, this study represents one of the few reports of a phage exhibiting broad-spectrum lytic activity against a well-characterized library of resistant P. aeruginosa strains. The results warrant further research to explore its potential as a phage therapy agent.