Staphylococcus aureus Sensitivity to Membrane Disrupting Antibacterials Is Increased under Microgravity.

Area of Science:

• Microbiology
• Space Biology
• Drug Discovery

Background:

• Staphylococcus aureus is a prevalent pathogen identified on the International Space Station (ISS).
• Microgravity is known to alter microbial physiology and antibiotic sensitivity, but its specific effects on S. aureus remain unclear.

Purpose of the Study:

• To investigate the impact of simulated microgravity (SMG) on Staphylococcus aureus.
• To assess changes in S. aureus lipid profiles and susceptibility to antibiotics under SMG.

Main Methods:

• Utilized high-aspect ratio vessels (HARVs) to simulate microgravity conditions.
• Analyzed changes in S. aureus fatty acid profiles (BCFAs and SCFAs) under SMG.
• Tested the efficacy of membrane-acting antibiotics (daptomycin, SDS, violacein) against S. aureus under SMG and normal gravity.

Main Results:

• SMG significantly altered S. aureus lipid profiles, increasing branch-chained fatty acids (BCFAs) and decreasing straight-chain fatty acids (SCFAs).
• This lipid shift led to a 12.1-fold increase in S. aureus killing by daptomycin under SMG.
• S. aureus showed enhanced susceptibility to SDS (22.9-fold) and violacein (12.8-fold) under SMG, confirming increased sensitivity to membrane-disrupting agents.

Conclusions:

• Simulated microgravity enhances the efficacy of membrane-active antibacterials against Staphylococcus aureus.
• These findings are critical for developing effective strategies to control S. aureus infections in space environments.
• The study suggests potential for increased potency of certain antibiotics against other pathogens in microgravity.