Comparative in-vitro antimicrobial activity of silver- and minocycline-rifampin-chlorhexidine-coated needle-free...

Needle-free connectors (NFCs) are widely used to access vascular infusion circuits. Despite their safety benefits, NFCs still present risks for colonization and vascular ingress by pathogenic microbes. Antimicrobial NFCs present one approach to prevent microbial colonization over all colonizable surfaces of NFCs, with the advantage of potentially protecting all vulnerable internal and external NFC surfaces.

This study compared a commercially available silver-coated NFC with a novel minocycline-rifampin-chlorhexidine (MRC)-coated NFC in an in-vitro model posing a severe microbial challenge following 1 and 7 days of elution in a 50% serum solution to simulate clinical use of the NFCs. Microbial challenges were performed against clinical isolates of meticillin-resistant Staphylococcus aureus (MRSA), multi-drug-resistant Pseudomonas aeruginosa and Candida albicans as representative of the major classes of highly virulent bloodstream infectious pathogens.

Results following 1 day of elution showed colonization of uncoated NFCs of 4.45 x 10⁶ colony-forming units (CFU)/NFC for MRSA, 5.20 x 10⁶ CFU/NFC for C. albicans and 3.68 x 10⁷ CFU/NFC for P. aeruginosa. The silver NFC presented approximately a 1 log₁₀ reduction for P. aeruginosa and similar colonization densities as the control for MRSA and C. albicans. In contrast, the MRC NFC showed no colonization by any of the challenge pathogens. Similar results were obtained following 7 days of elution.

The differences between the MRC and silver NFCs were significant (P<0.005). The MRC NFC has potential to reduce line infections, and therefore merits further in-vivo and clinical testing.