Antibiotics are arguably the most important and successful medicines of all time. However, bacteria have evolved resistance towards many individual antibiotics. Therefore, empirical drug combination therapies are often prescribed to try and suppress the development of antibiotic-resistant bacteria. A major knowledge gap is the impact of such combinations on the evolution of antibiotic resistance. Laboratory investigations have partially addressed this gap but cannot reproduce the conditions encountered during infection. There is therefore an urgent need to investigate resistance evolution in a system that reflects the infectious situation. The proposed research combines high level expertise in antibiotic drug combinations (China), evolution of resistance, and in vivo infections (NZ) to investigate the impact of antibiotic combinatorial treatments on a key bacterial pathogen, Pseudomonas aeruginosa. The outcomes of this study will help to understand and predict the best clinical combination strategy for patient care in both countries.