The Metabolic State of E. coli Influences Fosfomycin Efficacy and Promotes Resistance Evolution

Area of Science:

• Microbiology
• Molecular Biology
• Antibiotic Resistance

Background:

• Fosfomycin is a phosphonic antibiotic inhibiting bacterial cell wall synthesis by targeting MurA.
• Bacterial resistance to fosfomycin typically arises from transporter loss or enzymatic inactivation.
• The influence of a bacterium's metabolic state on fosfomycin efficacy remains largely uncharacterized.

Purpose of the Study:

• To identify metabolic activities influencing fosfomycin efficacy in *Escherichia coli*.
• To investigate the mechanisms underlying bacterial regrowth and fosfomycin resistance evolution.

Main Methods:

• Utilized an *Escherichia coli* CRISPR interference library targeting 1,515 metabolic genes.
• Employed population analysis profile tests and repeated treatment cycles to study regrowth phenotypes.
• Conducted whole-genome sequencing, metabolome analysis, and transcriptome analysis.

Main Results:

• Knockdowns of ATP synthase and pyruvate kinase genes induced a regrowth phenotype in *E. coli* exposed to fosfomycin.
• Evidence suggests heteroresistant populations may drive the evolution of fosfomycin resistance.
• A mutation in the *ibaG* gene conferred fosfomycin resistance, and phosphoenolpyruvate accumulated in regrowing cells, potentially competing with fosfomycin for MurA binding.
• Upregulation of cell envelope stress response genes, such as *cpxP*, was observed.

Conclusions:

• Bacterial metabolic state significantly modulates fosfomycin efficacy.
• Metabolic dysregulation can contribute to the evolution of fosfomycin resistance.
• Understanding these metabolic links is crucial for developing strategies to combat antibiotic resistance.