# Amikacin-eravacycline combination mediates the synergistic elimination of carbapenem-resistant pathogens via in vitro and in vivo metabolic reprogramming

## TL;DR

Combining amikacin and eravacycline with methionine effectively kills drug-resistant bacteria by causing oxidative stress and disrupting metabolism.

## Contribution

A novel antibiotic combination with methionine is shown to synergistically eliminate carbapenem-resistant pathogens through metabolic reprogramming.

## Key findings

- The AMK-ERV combination increases reactive oxygen species and oxidative stress in drug-resistant bacteria.
- Methionine enhances the antibacterial activity of ERV both in vitro and in vivo.
- The combination improves survival in mouse models of intra-abdominal infections caused by CR pathogens.

## Abstract

Carbapenem-resistant (CR) organisms (CRO) have been identified as critical priority pathogens, emphasizing the urgent need for novel therapeutic strategies. Combination therapy emerges as a promising approach to address multidrug-resistant bacterial infections. Here we demonstrate that eravacycline (ERV), in combination with amikacin (AMK), effectively eliminates a panel of clinically isolated CR Escherichia coli, CR Klebsiella pneumoniae, and CR Acinetobacter baumannii. Mechanistically, the AMK-ERV combination enhances bacterial oxidative phosphorylation, leading to an accumulation of reactive oxygen species, which induce oxidative stress and accelerate bacterial cell death. Notably, this combination significantly improves survival rates in mouse models of intra-abdominal infection, demonstrating efficacy against infections induced by CR pathogens. Furthermore, serum metabolomics reveals that the AMK-ERV combination upregulates metabolic pathways of lipids and amino acids. Interestingly, the amino acid methionine significantly enhances the antibacterial activity of ERV against CR pathogens both in vitro and in vivo. Our findings underscore the potential of repurposing AMK in combination with ERV to combat CR pathogens and propose a novel strategy for controlling these infections through the combination of antibiotics with specific metabolites such as methionine.

Carbapenem-resistant (CR) bacterial infections are a growing threat to global health and are becoming increasingly difficult to treat with existing drugs. Instead of developing new antibiotics, we explored more effective strategies using currently available medicines. We found that combining eravacycline (ERV), a recently approved antibiotic, with amikacin (AMK), a conventional and widely used drug, effectively eradicates multiple clinical isolates of CR pathogens. This combination disrupts bacterial energy metabolism and triggers overwhelming oxidative stress that leads to bacterial cell death. Unexpectedly, serum metabolomic analysis identified methionine, a natural amino acid, as a key factor that further enhances the activity of ERV. In a mouse model of intra-abdominal infection, this combination significantly reduced bacterial burden and improved survival. Mechanistically, this effect operates independently of the proton motive force, distinguishing it from the potentiation mechanism of tigecycline. Our findings highlight bacterial metabolism as a critical contributor to antibiotic efficacy and suggest that combining existing antibiotics with specific metabolic factors represents a practical therapeutic strategy against drug-resistant infections.