With a decline in antibiotic effectiveness, there is a renewed interest in bacteriophage (phage) therapy. Phages are bacterial-specific viruses that can be used alone or in combination with antibiotics to reduce bacterial load. Most phages are unsuitable for therapy because they are ‘temperate’ and can integrate into the host genome, protecting the host from subsequent phage infections. However, the integrated phage can be awakened by stressors such as DNA-damaging antibiotics. Parallel work from the lab uncovered strong synergy between a model temperate phage and sublethal ciprofloxacin, a fluoroquinolone, resulting in eradication of the phage’s Escherichia coli host. This project explores the potential of combined temperate phage-antibiotic synergy against a clinically relevant multi-drug resistant pathogen, Pseudomonas aeruginosa. Temperate phages infecting P. aeruginosa PA14 were isolated from the McMaster Wright clinical isolate collection. These phages were screened for synergy with six antibiotics (ciprofloxacin, levofloxacin, meropenem, piperacillin, tobramycin, polymyxin B), spanning four classes, using checkerboard assays. Surprisingly, our screen identified phages that can synergize with each of these antibiotics, despite their widely differing mechanism of action. One of the strongest pairings with ciprofloxacin was studied in further detail to understand the mechanism. This combination reduced the survivor count 10⁸ fold compared to the untreated host, corresponding to complete bacterial eradication. This was a result of the antibiotic preventing phage dormancy.  Ciprofloxacin also worked in combination with multiple phages even in clinical hosts resistant to the antibiotic, re-sensitizing the bacteria. Preliminary results show that combination of phage and piperacillin, a common anti-pseudomonal antibiotic, can increase Caenorhabditis elegans lifespan after an established P. aeruginosa infection. This is the first in vivo testing of temperate phage-antibiotic use. Overall, our findings indicate that temperate phages can act as adjuvants alongside our currently available antibiotics, drastically expanding their therapeutic potential.