Characterization of bacteriophages PAA and PAM and evaluation of their antibiotic synergy against Pseudomonas aeruginosa PAZMYU isolated from urine sample

Antibiotic resistance has been attributed to both the overuse of current drugs and the lack of availability of newer drugs due to stringent regulatory requirements and reduced commercial incentives. Novel alternative therapies, such as phage treatments, have demonstrated promising outcomes in clinical trials, indicating their potential for treating recalcitrant infections in the future. The objective of this study was to isolate and characterize bacteriophages against a uropathogenic strain of Pseudomonas aeruginosa and evaluate the antimicrobial efficacy of combining sub-inhibitory concentrations of cefepime and meropenem with the isolated bacteriophages. The isolated phages were designated PAA and PAM, both exhibiting icosahedral heads and long non-contractile tails. Both phages maintained stability within Limited pH and temperature ranges. The optimal adsorption times for PAA and PAM were 10 and 20 min, respectively, with PAA demonstrating a short latent time and burst size of 47, while PAM exhibited a burst size of 83. The optimal multiplicity of infection for PAA was 1, and for PAM was 0.1. PAA demonstrated efficacy against 40% of the tested strains of P. aeruginosa, while PAM was effective against 64%. Both phages remained stable at subinhibitory concentrations of cefepime and meropenem and when employed with sub-inhibitory concentrations of cefepime and meropenem, exhibited synergistic effects against planktonic bacterial cells and demonstrated efficacy in both biofilm inhibition and eradication.