An effective and biocompatible antibiofilm coating for central venous catheter

A Glance at Antimicrobial Strategies to Prevent Catheter-Associated Medical Infections

Urinary and intravascular catheters are two of the most used invasive medical devices; however, microbial colonization of catheter surfaces is responsible for most healthcare-associated infections (HAIs). Several antimicrobial-coated catheters are available, but recurrent antibiotic therapy can decrease their potential activity against resistant bacterial strains. The aim of this Review is to question the actual effectiveness of currently used (coated) catheters and describe the progress and promise of alternative antimicrobial coatings. Different strategies have been reviewed with the common goal of preventing biofilm formation on catheters, including release-based approaches using antibiotics, antiseptics, nitric oxide, 5-fluorouracil, and silver as well as contact-killing approaches employing quaternary ammonium compounds, chitosan, antimicrobial peptides, and enzymes. All of these strategies have given proof of antimicrobial efficacy by modifying the physiology of pathogens or disrupting their structural integrity. The aim for synergistic approaches using multitarget processes and the combination of both antifouling and bactericidal properties holds potential for the near future. Despite intensive research in biofilm preventive strategies, laboratorial studies still present some limitations since experimental conditions usually are not the same and also differ from biological conditions encountered when the catheter is inserted in the human body. Consequently, in most cases, the efficacy data obtained from in vitro studies is not properly reflected in the clinical setting. Thus, further well-designed clinical trials and additional cytotoxicity studies are needed to prove the efficacy and safety of the developed antimicrobial strategies in the prevention of biofilm formation at catheter surfaces.

An external ventricular drainage catheter impregnated with rifampicin, trimethoprim and triclosan, with extended activity against MDR Gram-negative bacteria: an in vitro and in vivo study

Background

External ventricular drainage (EVD) carries a high risk of ventriculitis, increasingly caused by MDR Gram-negative bacteria such as Escherichia coli and Acinetobacter baumannii. Existing antimicrobial EVD catheters are not effective against these, and we have developed a catheter with activity against MDR bacteria and demonstrated the safety of the new formulation for use in the brain.

Objectives

Our aim was to determine the ability of a newly formulated impregnated EVD catheters to withstand challenge with MDR Gram-negative bacteria and to obtain information about its safety for use in the CNS.

Methods

Catheters impregnated with three antimicrobials (rifampicin, trimethoprim and triclosan) were challenged in flow conditions at four weekly timepoints with high doses of MDR bacteria, including MRSA and Acinetobacter, and monitored for bacterial colonization. Catheter segments were also inserted intracerebrally into Wistar rats, which were monitored for clinical and behavioural change, and weight loss. Brains were removed after either 1 week or 4 weeks, and examined for evidence of inflammation and toxicity.

Results

Control catheters colonized quickly after the first challenge, while no colonization occurred in the impregnated catheters even after the 4 week challenge. Animals receiving the antimicrobial segments behaved normally and gained weight as expected. Neurohistochemistry revealed only surgical trauma and no evidence of neurotoxicity.

Conclusions

The antimicrobial catheter appears to withstand bacterial challenge for at least 4 weeks, suggesting that it might offer protection against infection with MDR Gram-negative bacteria in patients undergoing EVD. It also appears to be safe for use in the CNS.