Merulinic acid C overcomes gentamicin resistance in Enterococcus faecium.

Area of Science:

• Microbiology
• Natural Product Chemistry
• Pharmacology

Background:

• Enterococci are significant hospital-acquired pathogens known for developing antibiotic resistance.
• Natural products have historically yielded successful antimicrobial agents.
• Identifying novel compounds against resistant bacteria is a critical unmet medical need.

Purpose of the Study:

• To screen a natural product library for compounds active against antibiotic-resistant enterococci.
• To isolate and characterize active compounds from the library.
• To investigate the mechanism of action and synergistic potential of the most promising compound.

Main Methods:

• Whole-cell screening assay using a gram-positive model organism.
• Isolation and structural elucidation of anacardic acids using spectroscopic data and chemical derivatization.
• Fluorescence microscopy to determine the cellular target.
• Assessment of ATP leakage.
• Synergy testing with gentamicin against Enterococcus faecium.

Main Results:

• A series of anacardic acids were isolated from the natural product library screening.
• Merulinic acid C demonstrated potent activity against antibiotic-resistant enterococci.
• Merulinic acid C targets the bacterial membrane, leading to rapid ATP leakage.
• Merulinic acid C exhibited synergistic effects with gentamicin against Enterococcus faecium.

Conclusions:

• Merulinic acid C is a promising lead compound for developing new therapies against drug-resistant enterococci.
• Targeting the bacterial membrane and inducing ATP leakage represents a viable strategy.
• Combination therapy with merulinic acid C and existing antibiotics like gentamicin could overcome resistance mechanisms.