ABX01 targets drug-sensitive and Multi-Drug Resistant (MDR) Gram-negative bacteria, including clinically-relevant strains of Enterobacteriaceae, P. aeruginosa, and A. baumannii. The novel features of this approach are: broad spectrum efficacy against Gram-negative bacterial infections; a dual mechanism of action (direct and immune-mediated action) to kill bacteria; and an ability to harness and re-direct naturally occurring effector antibodies.