Nitazoxanide potentiates polymyxin B against Escherichia coli by inhibiting energy metabolism enzymes

Abstract

Background

Combination therapy has proven to be one of the viable strategies to effectively reduce the risk of resistance in antimicrobial treatment. The antiprotozoal agent nitazoxanide (NTZ) has been found to enhance the antimicrobial effects of colistin as a potential adjuvant for colistin therapy, but the details of this mechanism are still not fully understood.

Methods

To detect and validate the role of energy metabolism enzyme in NTZ promoting polymyxin B (PMB) against Escherichia coli (E. coli). The ability of NTZ to enhance PMB against E. coli was evaluated in vitro, along with the changes in ROS, ATP, and reduced coenzyme. The possible target genes of NTZ synergistic with PMB were explored by constructing gene deletion and overexpression strains.

Results

NTZ significantly inhibited the production of ATP, NAD⁺ and NADH and reduced the NAD⁺/NADH ratio, but aggravated polymyxin B (PMB) induced oxidative stress in E. coli. For strains with nuoC, aceE and aceF gene deletion, the sensitivity to PMB was significantly increased, while the synergistic effect of PMB with NTZ was decreased. The reactive oxygen species production of gene deletion strains was consistent with the synergistic effect.

Conclusions

NTZ blocks electron transport in the respiratory chain by inhibiting energy metabolizing enzyme activity, thereby leading to intracellular ATP depletion and oxidative stress, ultimately enhancing the antibacterial effect of PMB and leading to E. coli cell death.