A Dalbavancin Lock Solution Can Reduce Enterococcal Biofilms After Freezing

Area of Science:

• Infectious Diseases
• Pharmacology
• Medical Microbiology

Background:

• Catheter-related bloodstream infections (C-RBSI) are frequently caused by staphylococci and enterococci.
• Previous studies confirmed the efficacy of frozen dalbavancin-heparin (DH) lock solutions against staphylococcal biofilms.
• Enterococcal biofilms pose a significant challenge in C-RBSI management.

Purpose of the Study:

• To evaluate the bioactivity of frozen dalbavancin (D) and DH lock solutions against enterococcal biofilms.
• To assess the impact of a 6-month freezing period on the efficacy of these solutions.
• To compare the effectiveness of D alone versus DH against Enterococcus faecalis and Enterococcus faecium.

Main Methods:

• Bioactivity was assessed over 6 months using colony-forming unit (cfu) counts and metabolic activity assays.
• Four strains each of Enterococcus faecalis and Enterococcus faecium were used to create biofilms.
• Solutions of DH (1 mg/ml) and D were tested, with comparisons made against baseline (month 0) and between solutions at 3 and 6 months.

Main Results:

• Dalbavancin (D) solution alone showed no significant reduction in bioactivity against enterococcal biofilms after 6 months of freezing.
• The DH solution demonstrated statistically and clinically significant reductions in metabolic activity against E. faecalis biofilms (51.8% vs. 77.8% reduction).
• However, the DH solution showed reduced bioactivity compared to D alone, particularly against E. faecalis, after freezing.

Conclusions:

• A frozen dalbavancin lock solution maintains bioactivity against enterococcal biofilms for up to 6 months.
• Combining dalbavancin with heparin in a lock solution reduces its efficacy against enterococcal biofilms.
• For enterococcal C-RBSI, it is recommended to administer heparin separately from frozen dalbavancin lock solutions.