Having spent the last five years deeply immersed in the advanced catheter market, coatings were ubiquitous. Without lubricious coatings, catheter technology cannot reach its target destination, be it the heart, the brain or other organs. One thing we didn’t hear much about was antimicrobial coatings, as these devices are sterile and only in the patient for a relatively short period of time. Avoiding thrombosis and enabling ease of navigation were paramount in this particular market space.
Shifting my focus to implanted technologies, in both orthopedic and trauma fixation applications, introduces a new landscape of antimicrobial coatings. As most of the readers know, procedures featuring these devices are associated with high levels of Hospital Acquired Infections (HAIs).
Interestingly enough, there are no fixed, contact-killing, anti-microbial coatings currently on the market. Coatings marketed as “antimicrobial” are of two types; antimicrobial releasing (e.g., silver or antibiotics); or antifouling. Antimicrobial releasing coatings decrease in bioactivity over time. These coatings also leach their biocides into the body (which can induce bacterial resistance or introduce complications from sensitivities to heavy metals).
A canvasing of the research on Noble metal nanoparticle (NMNPs) coatings, in particular alloys composed of gold, silver, platinum and/or palladium, have garnered a fair amount of clinical interest. These heavy metals sidestep the problems associated with antibiotic resistant strains of bacteria, and have been demonstrated to be efficacious across a broad spectrum of bacteria.
However, further exploration of the literature reveals a primary concern with NMNPs, and I’ll quote, “Finally, it’s important to balance antibacterial efficiency and metallic poisoning, specifically for safety assessment in biomedical application.”
Antifouling, or non-adhesive coatings, have no antimicrobial activity and only postpone bacterial infections temporarily. The concepts behind antifouling coatings actually goes back to the use of copper in the bottom paint for ships. The copper flakes away as barnacles attach to the paint, thus the anti-fouling effect.
Contact-killing coatings, on the other hand, often leverage mechanical action. One example of a new, contact-killing, fixed coating is from Bioprex Medical (https://bioprexmedical.com/). Contact-killing coatings are considered to be the most promising as they do not leach biocides or heavy metals, do not exhibit diminishing efficaciousness over time, and kill bacterial by disrupting bacterial cell membranes and metabolic function. This approach precludes the ability of bacteria to attach to the coated surface and initiate colonization. From a single cell of bacteria, colonization initiates, rapidly resulting in the formation of biofilm.
This last benefit, of precluding the formation of biofilm, may in fact be the most significant aspect of Bioprex’s technology. Biofilms contribute to antimicrobial resistance (AMR) due to the depth and complexity of the biofilm environment. Studies indicate bacteria living in a biofilm can exhibit a 10 to 1,000 fold increase in antibiotic resistance compared to bacteria presenting in a planktonic state. Biofilms are often polymicrobial, adding to the challenge of treatment. The fact of the matter is, the best way to treat biofilms is to prevent their formation in the first place.
For more information, please contact Terry Murray at firstname.lastname@example.org.
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