Together with our colleagues in India, we systematically investigated phage-antibiotic synergy that is important for the implementation of phage therapy in clinics as phages are often used in combination with antibiotics. In this study, we tested different sub-lethal concentrations of various antibiotics together at different phage numbers using the model system of a Citrobacter phage together with its host Citrobacter amalonaticus. Citrobacter species are emerging opportunistic pathogens which can cause infections in animals (from shrimp and fish to mammals) and also humans.