Synergy of ATP and Meropenem in Stimulating the TCA Cycle to Enhance Killing of Carbapenem-Resistant Acinetobacter baumannii

Abstract

The global prevalence of carbapenem-resistant Acinetobacter baumannii (CRAB) represents a substantial concern for public health. Exogenous adenosine triphosphate (ATP) affects the bactericidal efficacy of meropenem against CRAB; however, the precise mechanism remains elusive. Here, reprogramming metabolomics was employed to delve into the mechanism underlying ATP-potentiated meropenem lethality against CRAB. Our findings reveal that ATP reprogramming activates the tricarboxylic acid (TCA) cycle in A. baumannii. Notably, the TCA cycle inhibitor malonate antagonised the synergistic bactericidal effect of ATP and meropenem. Activation of the TCA cycle stimulated riboflavin metabolism pathway and the electron transport chain, leading to increased reactive oxygen species (ROS) production. Hydrogen peroxide (H₂O₂) enhanced meropenem-mediated killing of CRAB, while the ROS scavenger α-tocopherol diminished the ATP-potentiated bactericidal effect. Additionally, ATP upregulated the gene expression of outer membrane porins, including omp33-36, oprD, ompW, and ompA, thereby improving membrane permeability and elevating intracellular levels of meropenem. The therapeutic synergy of ATP with meropenem was validated in a mouse model of acute pneumonia. This study not only highlights the potential of ATP as a co-treatment with meropenem but also elucidates the mechanisms by which ATP reverses CRAB resistance, specifically through the promotion of ROS production and enhanced membrane permeability.