Mutations in pmrB Confer Cross-Resistance between the LptD Inhibitor POL7080 and Colistin in Pseudomonas aeruginosa

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Drug Resistance

Background:

• Pseudomonas aeruginosa is a significant opportunistic pathogen.
• Increasing antibiotic resistance poses a major global health threat.
• Novel antibiotics targeting essential bacterial processes are under development.

Purpose of the Study:

• To investigate the resistance mechanisms of Pseudomonas aeruginosa against POL7080, a novel antibiotic targeting lipopolysaccharide transport.
• To identify genetic mutations conferring resistance to POL7080.

Main Methods:

• Isolation and characterization of POL7080-resistant Pseudomonas aeruginosa strains.
• Genetic analysis to identify mutations, focusing on the pmrB gene.
• Transcriptomic analysis to understand gene expression changes.
• Confocal microscopy to visualize bacterial cell surface changes.

Main Results:

• Specific mutations in the pmrB gene were identified in POL7080-resistant strains.
• These mutations led to modifications in the bacterial lipopolysaccharide (LPS).
• LPS alterations were shown to decrease the binding of POL7080 to the bacterial cell surface.
• The observed resistance mechanism is similar to that seen with colistin.

Conclusions:

• The PmrB two-component system plays a crucial role in mediating resistance to POL7080 in Pseudomonas aeruginosa.
• Lipopolysaccharide modification is a key mechanism for evading POL7080.
• Understanding these resistance pathways is vital for the development of effective anti-pseudomonal therapies.