Induction of Daptomycin Tolerance in Enterococcus faecalis by Fatty Acid Combinations

Area of Science:

• Microbiology
• Bacterial Physiology
• Antibiotic Resistance

Background:

• Enterococcus faecalis is a common cause of hospital-acquired infections.
• Serum supplementation confers tolerance to daptomycin, a key antibiotic.
• Specific fatty acids in serum mediate this daptomycin tolerance.

Purpose of the Study:

• Investigate how combinations of protective and nonprotective fatty acids influence E. faecalis physiology and daptomycin tolerance.
• Determine the role of cell envelope charge in fatty acid-induced daptomycin tolerance.

Main Methods:

• Supplementation of E. faecalis cultures with various combinations of specific fatty acids (oleic, linoleic, palmitic, stearic).
• Measurement of physiological responses including growth, morphology, and membrane fluidity.
• Assessment of daptomycin tolerance in response to fatty acid supplementation.

Main Results:

• Nonprotective fatty acids (palmitic, stearic) caused growth and morphology defects, rescued by protective fatty acids (oleic, linoleic).
• Protective fatty acids restored membrane fluidity reduced by nonprotective fatty acids.
• Combinations of protective and nonprotective fatty acids induced daptomycin tolerance, some as effectively as serum.

Conclusions:

• Daptomycin tolerance in E. faecalis is primarily driven by specific protective fatty acids found in serum.
• Cell envelope charge does not correlate with the observed fatty acid-induced daptomycin tolerance.
• Understanding fatty acid interplay is crucial for combating antibiotic tolerance in clinical settings.