Effect of Antibiotic Exposure on Staphylococcus epidermidis Responsible for Catheter-Related Bacteremia

Area of Science:

• Microbiology
• Infectious Diseases
• Genomics

Background:

• Coagulase-negative staphylococci (CoNS), particularly Staphylococcus epidermidis, are significant causes of healthcare-associated infections, especially with indwelling medical devices like catheters.
• Catheter-related bacteremia (CRB) leads to increased healthcare costs and patient mortality.

Purpose of the Study:

• To investigate the effects of sub-inhibitory antibiotic concentrations on resistance, fitness, and genome evolution in Staphylococcus epidermidis strains causing CRB.
• To evaluate the impact of 15-day exposure to ceftobiprole, daptomycin, linezolid, and vancomycin.

Main Methods:

• Antibiogram testing to assess resistance.
• Biofilm Ring test® and nematode virulence model to evaluate metabolic adaptation and fitness.
• Whole-genome sequencing (WGS) to determine genomic changes.
• Biofilm formation experiments to quantify biofilm development.

Main Results:

• Staphylococcus epidermidis strains exhibited diverse virulence and biofilm formation capabilities.
• Antibiotic exposure led to increased biofilm formation, indicating adaptation in bacterial fitness.
• Antibiotic exposure altered genes associated with resistance, inducing cross-resistance between vancomycin, daptomycin, and ceftobiprole.

Conclusions:

• Sub-inhibitory antibiotic exposure significantly modifies bacterial pathogenicity and promotes the emergence of resistant Staphylococcus epidermidis strains.
• This adaptation highlights the potential for increased virulence and resistance in bacteria exposed to low antibiotic concentrations in clinical settings.