Genomic Insights into and Lytic Potential of Native Bacteriophages M8-2 and M8-3 Against Clinically Relevant Multidrug-Resistant Pseudomonas aeruginosa.

Background/

Objectives: Antibiotic resistance in pathogenic bacteria poses a critical global health threat, with multidrug-resistant (MDR) strains increasingly undermining conventional treatments. Among these, Pseudomonas aeruginosa is a high-priority pathogen due to its resistance to carbapenems and frequent presence in hospital settings, contributing to severe healthcare-associated infections. This study aimed to isolate and characterize novel bacteriophages from environmental wastewater samples that could specifically target MDR P. aeruginosa.

Methods: Two bacteriophages, M8-2 and M8-3, were isolated from wastewater in Monterrey, Mexico. A genomic analysis classified M8-2 and M8-3 within the Caudoviridae family, and next-generation sequencing (NGS) was used to confirm the absence of undesirable antibiotic resistance or virulence genes. Optimization of viral amplification was performed to achieve high titers, with structural proteins characterized by SDS-PAGE.

Results: Phages M8-2 and M8-3 exhibited specific lytic activity against MDR strains of P. aeruginosa, offering a targeted approach to combat antibiotic-resistant infections. High genetic similarity (>95%) to known Gram-negative bacterial phages was observed. Optimized viral amplification yielded titers of 4.2 × 107 and 1.03 × 109 PFUs/mL for M8-2 and M8-3, respectively. The specificity of these phages minimized disruption to the host microbiome, and their significant efficacy in suppressing bacterial growth positions bacteriophages as promising candidates for localized and personalized phage therapy, especially in chronic and hospital-acquired infection settings.

Conclusions: These findings highlight the therapeutic potential of M8-2 and M8-3 in addressing antibiotic-resistant P. aeruginosa infections. Their safety profile, high target specificity, and robust lytic activity underscore the feasibility of incorporating phage-based strategies into current antimicrobial protocols. This study contributes to the broader goal of developing sustainable and effective phage therapies for diverse clinical and environmental contexts.