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Researchers Report Three Distinct Strategies to Counter Antibiotic Resistance in Bacterial Infections

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New Research Tackles Antibiotic Resistance from Multiple Angles

Study 1: Horizontal Gene Transfer of Resistance in Cystic Fibrosis Patients

Researchers at the University of Washington School of Medicine published a study in Nature Microbiology on July 23, reporting a mechanism of rapid antibiotic resistance development in cystic fibrosis (CF) patients.

Key Findings

In some CF patients, antibiotic resistance increased more than 10,000-fold shortly after treatment began.

  • Short-read sequencing did not identify mutations in bacterial genomes that could account for this rapid increase.
  • Long-read sequencing revealed that lung pathogens had acquired circular DNA structures called plasmids containing new resistance genes.
  • Environmental bacteria appearing transiently in lung samples before resistance developed were found to carry identical resistance plasmids.

Mechanism

The study indicates that environmental bacteria can transfer resistance-carrying plasmids to antibiotic-sensitive pathogens already established in the lungs, resulting in an immediate increase in resistance. Previously, resistance was understood to develop gradually through mutation accumulation.

Broader Implications

The authors suggest that environmental bacteria may also transfer genes that assist pathogens in acquiring nutrients, blocking immune responses, or breaking down barriers to infection spread. Proposed mitigation strategies include environmental monitoring, containment, and blocking gene transfer.

Funding

The research was supported by the Cystic Fibrosis Foundation (KARASH23F0, SINGH22A0, SINGH19R0) and the National Institutes of Health (AI127472, 1R01HL160810-01).

Study 2: Chemical Inhibition of Bacterial Immune Systems

The Gerdt Lab at Indiana University Bloomington published a study in Cell Host and Microbe identifying a chemical molecule that inhibits a bacterial immune system, potentially making bacteria more susceptible to bacteriophages.

Key Findings

This represents the first identified small molecule capable of chemically inhibiting a bacterial immune system.

  • The molecule, when combined with a bacteriophage (a virus that infects and kills bacteria), helps the virus overcome a bacterium's immune response.
  • The immune system targeted is present in approximately 2,000 different bacterial species, including Pseudomonas aeruginosa and Staphylococcus aureus.

Context

Bacteriophages offer a potential alternative to antibiotics, as they can be deployed to target specific problematic bacterial strains. However, bacteria can develop immunity to bacteriophages, similar to antibiotic resistance.

Research Status

The Gerdt Lab's long-term objective is to develop a library of inhibitors for various bacterial species, a process expected to take 10 to 15 years. The research team noted that antibiotics are expected to remain the primary treatment for human bacterial infections, though the findings may be applicable to hard-to-treat infections and agricultural settings.

Study 3: Targeting Protein-Folding to Disable Resistance and Cross-Protection

A study published in eLife describes a mechanism that disables antibiotic resistance in bacteria and disrupts a process called cross-protection.

Key Findings

Cross-protection occurs when resistant bacteria degrade antibiotics in their environment, lowering drug concentrations and allowing nearby susceptible bacteria to survive.

  • Researchers targeted a protein-folding system essential for the function of bacterial resistance enzymes.
  • Both genetic deletion of the protein-folding gene and chemical inhibition of the system deactivated resistance enzymes and sensitized bacteria to β-lactam antibiotics.
  • Experiments in wax moth larvae and mixed bacterial communities showed that disrupting the folding system prevented one bacterial species from protecting another.

Research Focus

The research focused on synthetic polymicrobial communities of Pseudomonas aeruginosa and Stenotrophomonas maltophilia, which are relevant to cystic fibrosis lung infections. S. maltophilia is highly resistant to antibiotics, including β-lactams, primarily through the production of β-lactamase enzymes.

Funding

The study was supported in part by the National Institute of Allergy and Infectious Diseases of the U.S. National Institutes of Health, the U.K. Medical Research Council, UT's Cockrell School of Engineering, the Fundação para a Ciência e a Tecnologia, I.P., the Welch Foundation, and the U.K. Biotechnology and Biological Sciences Research Council.

Study 4: Antibiotic Redesign to Overcome Efflux Pump Resistance

A study led by King's College London and published in the Journal of Medicinal Chemistry describes an approach called "Efflux Resistance Breaker" (ERB).

Key Findings

The approach involves chemically redesigning antibiotics to be less susceptible to removal by bacterial efflux pumps.

  • This allows higher concentrations of the antibiotic to remain inside bacterial cells.
  • The resistance-breaking properties are built directly into the antibiotic molecule, unlike previous strategies that combined antibiotics with separate efflux pump inhibitors.