Antimicrobial elution patterns correlate with antibacterial and antifungal activities of three antimicrobial central...

Antimicrobial central venous catheters (CVCs) help prevent CVC-related bloodstream infection (CRBSI), and their effectiveness depends on sustaining broad antimicrobial activity in serum. A new CVC containing minocycline, rifampin, and chlorhexidine (MRC) was recently approved, complementing existing minocycline-rifampin (MR) and chlorhexidine-silver-sulfadiazine (CSiSz) CVCs. This study compared the elution profiles of minocycline, rifampin, and chlorhexidine from these three CVC types in serum and assessed resulting antimicrobial durability against CRBSI pathogens. MRCs were prepared by impregnation with minocycline and rifampin, followed by sequential chlorhexidine coating; commercial MR and CSiSz CVCs served as comparators. CVCs were immersed in plasma for 24 h, and then in serum for 3 weeks. At baseline and weekly intervals, CVC segments were analyzed for antimicrobial content and challenged with clinical CRBSI isolates. MRC retained higher minocycline and rifampin levels than MR and higher chlorhexidine levels than CSiSz after 3 weeks in serum. Correspondingly, MRC demonstrated superior inhibition of gram-negative colonization (Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii) and Enterococcus faecalis at week 3 (P ≤ 0.028). They also showed greater activity against Candida species (spp.) (C. albicans, C. glabrata) at weeks 2 and 3 (P ≤ 0.005). MR and MRC CVCs completely prevented methicillin-resistant Staphylococcus aureus and S. epidermidis colonization for 3 weeks, outperforming CSiSz (P = 0.003). In conclusion, slow elution from MRC CVCs resulted in significantly enhanced antimicrobial durability against gram-negative bacteria, E. faecalis, and Candida spp. MR and MRC CVCs provided equivalent, sustained protection against Staphylococcal colonization, both surpassing CSiSz CVCs.