Macrolide accumulation by Bacteroides fragilis ATCC 25285

Area of Science:

• Microbiology
• Pharmacology
• Bacterial Physiology

Background:

• Bacteroides fragilis is a significant Gram-negative bacterium.
• Understanding antibiotic accumulation is crucial for treating infections caused by B. fragilis.
• Macrolide antibiotics are widely used, but their efficacy against certain bacteria can vary.

Purpose of the Study:

• To investigate the accumulation of macrolide antibiotics in Bacteroides fragilis ATCC 25285.
• To determine the relationship between macrolide hydrophobicity and their accumulation, efflux, and antibacterial activity.
• To elucidate the mechanism underlying the susceptibility of B. fragilis to macrolides.

Main Methods:

• Quantification of macrolide antibiotic accumulation in B. fragilis ATCC 25285.
• Measurement of macrolide efflux half-times.
• Determination of Minimum Inhibitory Concentrations (MICs) for different macrolides.
• Correlation analysis between antibiotic hydrophobicity and accumulation/activity.

Main Results:

• Macrolide accumulation in B. fragilis increased with hydrophobicity in the order: erythromycin < josamycin < rokitamycin.
• Efflux half-times of macrolides were prolonged in the same order of increasing hydrophobicity.
• Minimum Inhibitory Concentrations (MICs) of macrolides were correlated with their hydrophobicity.

Conclusions:

• Macrolide antibiotics accumulate in B. fragilis primarily due to their hydrophobic properties.
• Efficient drug accumulation, driven by hydrophobicity, likely contributes to the observed susceptibility of this Gram-negative bacterium to macrolides.
• The findings provide insights into the pharmacokinetics and pharmacodynamics of macrolides in B. fragilis.