A novel phage encoding host defense modulators demonstrates in-vivo therapeutic efficacy against carbapenem-resistant E. coli ST1432

This study aimed to isolate, identify, characterize, and evaluate in vivo therapeutic efficacy of a lytic bacteriophage against carbapenem-resistant E. coli (CREC). A lytic bacteriophage was isolated from wastewater. The biological properties including morphology, burst size, latent period, optimal MOI, stability of pH and temperature, and host specificity were determined. Its genomic feature was analyzed by whole genome sequencing. The in vivo therapeutic efficacy was evaluated by Galleria mellonella infection model against clinical isolate of CREC ST1432 as an emerging One Health MDR threat. The one-step-growth curve revealed a latent period of 20 min and a burst size of 116 PFU/cell. The phage was stable between 4–60 °C and pH 4–10. The dsDNA genome of Baskent_Phicoli_1 is composed of 39,500 bp with 50.06% GC content. Comprehensive genome analysis confirmed the absence of antimicrobial resistance, virulence, and lysogeny encoding genes. In the untreated infection group (IC), which received a lethal dose of CREC, 73.3% of the larvae died, whereas the survival rate was 100% in both the phage treatment (PT) and toxicity control groups. Extensive melanized nodules were observed in IC, while larvae in PT group exhibited reduced tissue damage in the fat body and muscle layers compared to IC. This study demonstrated the potential of Baskent_Phicoli_1 as a promising candidate for phage therapy against CREC. Significantly, the phage genome encodes genes for an RNA polymerase inhibitor and an OCR-like anti-restriction protein. The presence of host defense modulators emphasizes the phage's ability to effectively break down bacterial defenses, highlighting its promise for biotechnological applications in combating bacterial infections.