Mature biofilms of Enterococcus faecalis and Enterococcus faecium are highly resistant to antibiotics

Area of Science:

• Microbiology
• Infectious Diseases
• Biomaterials Science

Background:

• Enterococcus faecalis and Enterococcus faecium are significant causes of hospital-acquired infections.
• These bacteria readily form biofilms on medical devices and implanted materials.
• Biofilm formation complicates antibiotic treatment and increases patient morbidity.

Purpose of the Study:

• To compare the antibiotic sensitivity of bacteria within newly formed versus mature enterococcal biofilms.
• To evaluate the efficacy of antibiotic treatments, including rifampicin combinations, against biofilms of different ages.

Main Methods:

• Bacterial biofilms of Enterococcus faecalis and Enterococcus faecium were established on bone cement beads over 24 hours (new) and 120 hours (mature).
• Minimal biofilm eradication concentrations (MBECs) were determined.
• Time-kill experiments were conducted to assess antibiotic efficacy.

Main Results:

• Mature biofilms exhibited significantly higher bacterial loads compared to new biofilms.
• Bacteria within mature biofilms demonstrated markedly increased tolerance to antibiotics.
• This enhanced tolerance was observed even with antibiotic combinations containing rifampicin.

Conclusions:

• Biofilm maturation significantly increases the tolerance of Enterococcus species to antibiotic treatment.
• Current antibiotic strategies may be less effective against established enterococcal biofilms on biomaterials.
• Further research is needed to develop effective treatments for biofilm-related enterococcal infections.