Abstract

Objective: The aim of this study is to compare the efficacy of catheter lock solutions of novel antibiotics with anticoagulants against methicillin-resistant Staphylococcus aureus (MRSA) embedded in biofilm.

Methods: Biofilm was formed in vitro on silicone Hickman catheter segments by 10 MRSA isolates. Catheter segments were exposed to 2 mg/ml vancomycin, teicoplanin, daptomycin, linezolid, tigecycline, and rifampin solutions for 24 hours. To evaluate the antimicrobial activities of antibiotics against MRSA, bacterial colonies were counted after catheters were vortexed in 0.9% saline. Additionally, as in antibiotic lock therapy, catheter segments were exposed to combination of vancomycin, teicoplanin, daptomycin, linezolid, and tigecycline with 1000 IU/ml heparin daily four hours for consecutive five days. Antimicrobial efficacy was assessed daily.

Results: After 24 hours of exposure, the most effective antibiotic was detected as daptomycin on the Hickman catheter segments. Both daptomycin and tigecycline decreased significantly the bacterial colony counts on the third day of 4-hour daily exposures (all p values were <0.01). There was no significant difference between these two antibiotics (p=0.993).

Conclusions: Both daptomycin and tigecycline are promising antimicrobial agents that can be used in antibiotic lock solution for the treatment of central line-associated bloodstream infections due to MRSA. This study provides encouraging data which should be validated in clinical settings.