Pyrrole-based inhibitors of RND-type efflux pumps reverse antibiotic resistance and display anti-virulence potential

Area of Science:

• Microbiology
• Pharmacology
• Biochemistry

Background:

• Resistance-nodulation-cell division (RND) superfamily efflux pumps, such as AcrAB-TolC and MexAB-OprM, are crucial for bacterial intrinsic and acquired resistance.
• These efflux pumps also play a significant role in the pathogenicity of Gram-negative bacteria.

Purpose of the Study:

• To identify novel pyrrole-based compounds that inhibit RND efflux pumps.
• To evaluate the potential of these inhibitors as antibiotic adjuvants to combat Gram-negative bacterial infections and virulence.

Main Methods:

• Molecular docking and biophysical studies to determine inhibitor-target interactions.
• Assays to assess efflux pump inhibition, antibiotic potentiation, and effects on bacterial physiology (persister formation, post-antibiotic effect).
• In vitro and in vivo studies evaluating anti-virulence and therapeutic efficacy in infection models.

Main Results:

• Pyrrole-based compounds were identified as inhibitors of RND transporters, binding to AcrB.
• These efflux pump inhibitors (EPIs) successfully inhibited probe efflux, reduced persister formation, extended post-antibiotic effect, and decreased resistant mutant development.
• EPIs demonstrated anti-pathogenic potential, attenuated P. aeruginosa virulence in vivo, and inhibited intracellular invasion of bacteria into macrophages.
• Combination therapy with EPIs and antibiotics showed significant efficacy in animal models of lung infection and sepsis, with negligible toxicity.

Conclusions:

• Novel pyrrole-based efflux pump inhibitors (EPIs) effectively target RND transporters in E. coli and P. aeruginosa.
• EPIs potentiate antibiotic activity, reduce bacterial virulence, and prevent resistance development without compromising bacterial membrane integrity.
• These EPIs represent promising antibiotic adjuvants for treating severe Gram-negative bacterial infections.