Identifying Metabolic Inhibitors to Reduce Bacterial Persistence

Area of Science:

• Microbiology
• Bacteriology
• Antimicrobial Resistance

Background:

• Bacterial persisters are rare, dormant cells tolerant to antibiotics.
• High redox activity in stationary-phase cells correlates with reduced protein production and growth.
• Endogenous degradation maintains redox activity, repressing antibiotic-targeted functions.

Purpose of the Study:

• To investigate if inhibiting redox activity can sensitize persister cells to antibiotics.
• To develop an assay for identifying drugs targeting persister metabolism.
• To validate identified drugs against persister phenotypes in relevant bacteria.

Main Methods:

• Pretreatment of stationary-phase cells with chlorpromazine hydrochloride (CPZ) to inhibit ATP synthase.
• Development of a degradable fluorescent protein assay with a library of FDA-approved drugs.
• Testing identified inhibitors against *Escherichia coli* and *Pseudomonas aeruginosa* persistence.

Main Results:

• CPZ pretreatment reduced stationary-phase redox activity and protein degradation, increasing antibiotic susceptibility.
• The assay identified polymyxin B, poly-L-lysine, and phenothiazine antipsychotics as persister-reducing agents.
• These agents also reduced persistence in *Pseudomonas aeruginosa*, suggesting conserved mechanisms.

Conclusions:

• Inhibiting persister cell redox activity is a viable strategy to enhance antibiotic efficacy.
• A novel assay can screen for drugs targeting persister metabolism.
• Identified compounds offer potential new avenues for combating bacterial persistence.