Pathogens that cause healthcare-associated infections (HAIs), for example, central line-associated bloodstream infection, catheter-associated urinary tract infection, surgical site infection, and ventilator-associated pneumonia, pose an ongoing and increasing challenge to healthcare facilities around the world. According to the Safe Care Campaign ( ) accessed June 9, 2014, HAIs result in more deaths in the US than AIDS, auto accidents, and breast cancer combined. As a result of this global issue, medical device manufacturers are looking to antimicrobial coatings.

Fig. 1 – Device manufacturers are looking to protect central-line and urinary catheters, ventilators, and more with antimicrobial technologies, in an effort to fight the rise of healthcare-associated infections.
Silver has been the foremost antimicrobial in use due to its success against a wide range of microorganisms. Generally, silver ions concentrate on the surface of the product to eliminate bacteria. The silver ions essentially bind with the bacteria and microbes, damaging their cells. This disrupts the bacteria’s normal function, stopping them from reproducing, causing the bacteria to die.

While silver ion technology has been generally accepted in the industry, medical device manufacturers have expressed concerns as the technology wears down in strength over time. While damaged pathogens cannot come back to life, new pathogens may be introduced. Also, high exposure or ingestion of highly concentrated forms of ionic silver may cause “argyria or argyrosis,” a permanent ashen-gray discoloration of skin.

Antibiotics containing antimicrobial solutions are also available and have shown effectiveness in some applications, but they are not without their disadvantages as well. The local and fast release of antibiotics could reduce the effectiveness for long-term use of catheters and other applications as their concentration drops below the minimal inhibitory concentration. Additionally, the use of high doses of antibiotics can result in antibiotic resistance, and antibiotics may have limited effectiveness against a wide range of microorganisms. (See Figure 1)

Antimicrobial Parylenes Offer Advantages

A newer alternative in the industry combines the benefits of biocompatible Parylene conformal coatings with antimicrobial properties to effectively eliminate harmful microorganisms. Parylene is an ultra-thin (micron-level), pinhole-free coating that is applied in a vapor deposition process. The molecular “growth” of Parylene coating ensures a uniform conformal coating that penetrates into every crevice, regardless of how seemingly inaccessible. Parylene coatings have a long history in the medical industry providing barrier properties against body fluids as well as moisture, chemicals, and common gases. The coating also possesses excellent dry-film lubricity characteristics. Parylenes N, C, and Parylene HT comply with the biological testing requirements of ISO 10993 and are certified to comply with the biological testing requirements for USP Class VI Plastics.

Antimicrobial Parylene technologies can protect any device that comes in contact with, or is placed into the body from a variety of microorganisms. Some common applications, and the most problematic sources for HAIs, include urinary and central-line catheters, ventilators, general elastomers (seals, O-rings, tubing), and urological tools, to name a few.

Antimicrobial Parylene technologies fill the gap of antimicrobial attributes for Parylene itself and offer an alternative to the limited reach of silver ion and antibiotic technologies. Such advances provide manufacturers an alternative technology in the fight against healthcare-associated infections, one that enables their devices to effectively eliminate and protect against harmful microorganisms.

This article was written by Rakesh Kumar, PhD, Vice President of Technology, Specialty Coating Systems, Inc., Indianapolis, IN. For more information, Click Here .

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