Antimicrobial resistance is of global concern, with 10 million deaths annually predicted by 2050 due to antibiotic-resistant infections. ESKAPE is an acronym created to identify six pathogens with increasing resistance in hospitals, namely Gram-positive Enterococcus sppand Staphylococcus aureus, and Gram-negative Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. These bacteria often carryplasmids encoding resistance genes for antibiotics and heavy metals, contributing significantly to the spread of antimicrobial resistance. IncP group plasmids have a broad host range and can spread genes across many gram-negative pathogens.

The project aimed to characterise P. aeruginosa phage G101 by sequencing its genome and examining the morphology via transmission electron microscopy. G101, which infects P. aeruginosa strain PAO9503, can achieve high titre (109 pfu/mL). However, the presence of an IncP plasmid reduces its infectivity by 1000-fold. To decipher this mechanism and identify the genes involved in infection, we generated mutant phages that were able to infect the Pseudomonas strain with equal efficiency, regardless of the plasmid presence. These mutants have alterations in a single hypothetical gene. Current efforts focus on cloning this gene into a Pseudomonas strain to test its role in infection blockage. Ultimately, this study aims to identify the phage gene responsible for reduced infection in the presence of a conjugative plasmid, providing insight for novel antimicrobial therapeutics developments.