Treatment of Gram-negative bacterial infections by potentiation of antibiotics. Posted on May 31, 2016 at 12:17 pm.Written by Spero Therapeutics Current Opinion in Microbiology 33, 7-12. DOI: 10.1016/j.mib.2016.05.005. Zabawa TP, Pucci MJ, Parr TR Jr, Lister T. (2016) Post navigation A Novel Polymyxin Derivative That Lacks the Fatty Acid Tail and Carries Only Three Positive Charges Has Strong Synergism with Agents Excluded by the Intact Outer Membrane.SPR741, an Antibiotic Adjuvant, Potentiates the In Vitro and In Vivo Activity of Rifampin against Clinically Relevant Extensively Drug-Resistant Acinetobacter baumannii