Title : Isolation, characterization, and therapeutic application of a newly isolated bacteriophage PAGP25 against multidrug-resistant Pseudomonas aeruginosa
Abstract:
Pseudomonas aeruginosa is a clinically important opportunistic pathogen responsible for a diverse range of healthcare-associated infections, including chronic wound infections, burn wound infections, pneumonia, and urinary tract infections. The rapid emergence and global dissemination of multidrug-resistant (MDR) P. aeruginosa have significantly compromised the efficacy of conventional antibiotic therapies, posing a major public health challenge. Consequently, alternative antimicrobial interventions such as bacteriophage therapy are being increasingly explored to combat antimicrobial resistance. In the present study, a newly isolated lytic bacteriophage, PAVP25, was isolated from the river Ganga, India, and comprehensively characterized for its biological, genomic, and therapeutic potential against MDR P. aeruginosa. Host range analysis demonstrated broad infectivity and potent lytic activity against a diverse collection of clinical MDR isolates. Ultrastructural examination by transmission electron microscopy revealed an icosahedral head and contractile tail morphology, classifying PAPV25 within the class Caudoviricetes. The phage exhibited remarkable stability across a wide range of environmental conditions, retaining infectivity at pH 4-11 and temperatures ranging from −20°C to 55°C. One-step growth kinetics indicated rapid replication, characterized by a short latent period and a high burst size. The antibacterial efficacy of PAVP25 was further evaluated through in vitro and in vivo studies. Phage treatment significantly suppressed bacterial growth and effectively disrupted established biofilms formed by MDR P. aeruginosa. Microscopic analyses revealed extensive damage to bacterial cells and biofilm architecture following phage exposure. Therapeutic efficacy was subsequently assessed in a murine wound infection model, where administration of PAVP25 led to a substantial reduction in bacterial load, accelerated wound closure, and improved survival outcomes compared with untreated controls. Whole-genome sequencing identified a double-stranded DNA genome. Functional annotation revealed genes involved in DNA replication, morphogenesis, packaging, and host cell lysis. Importantly, no genes associated with lysogeny, antimicrobial resistance, bacterial virulence, or known toxins were detected, supporting the safety profile of PAVP25 for therapeutic applications. Therefore, these findings establish PAVP25 as a highly effective lytic bacteriophage with potent antibacterial and antibiofilm activity against MDR P. aeruginosa. The demonstrated therapeutic efficacy and favorable genomic characteristics underscore its potential as a promising biocontrol agent and alternative antimicrobial strategy for managing drug-resistant infections and mitigating the growing burden of antimicrobial resistance.
