Significance: Exogenous metabolites have been documented to potentiate antibiotics to kill multidrug-resistant pathogens, but the mechanisms are largely unknown. The work presented here shows that intermetabolites from the TCA cycle and the phosphoenolpyruvate (PEP)-pyruvate-AcCoA pathway have the potential to improve targeting of these resistant microorganisms. The enzymes that connect the PEP-pyruvate-AcCoA pathway to the TCA cycle are essential for this potentiation, indicating both pathway and cycle can be merged to be considered a pyruvate cycle (P cycle). The P cycle operates routinely as a general mechanism for energy production and regulating the TCA cycle in Escherichia coli and Edwardsiella tarda . The results reported here provide insights into metabolite-facilitated targeting by antibiotics as well as bacterial energy metabolism and homeostasis.

Multidrug-resistant Escherichia coli metabolomes are reprogrammed by glutamine to be sensitive to ampicillin in vitro and in vivo.

Summary: Antibiotic‐resistant Vibrio alginolyticus poses a big challenge to human health and food safety. It is urgently needed to understand the mechanisms underlying antibiotic resistance to develop effective approaches for the control. Here we explored the metabolic difference between gentamicin‐resistant V . alginolyticus (VA‐R _GEN ) and gentamicin‐sensitive V . alginolyticus (VA‐S), and found that the reactive oxygen species (ROS) generation was altered. Compared with VA‐S, the ROS content in VA‐R _GEN was reduced due to the decreased generation and increased breakdown of ROS. The decreased production of ROS was attributed to the decreased central carbon metabolism, which is associated with the resistance to gentamicin. As such a mechanism, we exogenously administrated VA‐R _GEN with the glucose that activated the central carbon metabolism and promoted the generation of ROS, but decreased the breakdown of ROS in VA‐R _GEN . The gentamicin‐mediated killing was increased with the elevation of the ROS level by a synergistic effect between gentamicin and exogenous glucose. The synergistic effect was inhibited by thiourea, a scavenger of ROS. These results reveal a reduced ROS‐mediated antibiotic resistance mechanism and its reversal by exogenous glucose.