Staphylococcus aureus persisters tolerant to bactericidal antibiotics

Area of Science:

• Microbiology
• Bacterial Physiology
• Antimicrobial Resistance

Background:

• Bacterial persister cells are phenotypic variants exhibiting tolerance to antibiotics.
• Understanding persister cell dynamics is crucial for combating persistent infections.

Purpose of the Study:

• To analyze Staphylococcus aureus persister cell levels and characteristics.
• To investigate factors influencing persister cell isolation and robustness.

Main Methods:

• Monitoring colony-forming unit counts of planktonically grown S. aureus strains.
• Treating cultures with six different antimicrobials at varying concentrations and growth phases.
• Analyzing killing kinetics and characterizing isolated persister subpopulations.

Main Results:

• Antibiotic tolerance was higher in small colony variant (SCV) strains and in stationary versus exponential growth phases.
• Biphasic killing kinetics indicated persister cell enrichment under various conditions.
• Persister isolation robustness varied with antibiotic type, concentration, and bacterial strain, with physiological heterogeneity observed within persister subpopulations.

Conclusions:

• S. aureus stationary phase cells are not equivalent to persisters, as not all showed antibiotic tolerance.
• The isolation of robust S. aureus persisters is contingent upon specific antibiotic and strain characteristics.
• This research contributes to understanding persister cell heterogeneity and its implications for antibiotic treatment.