Sealing Shielding

Antimicrobial Compounds Combat HAIs

Antimicrobial Compounds Combat HAIs, Antimicrobial PolyisoprenesHealthcare-associated infections (HAIs), aka hospital-acquired infections are caused by viral, bacterial, and fungal pathogens. People, while receiving treatment for different medical conditions at a health care facility, hospital or other, can acquire HAIs. The National and State Healthcare-Associated Infections Progress Report (HAI Progress Report) issued by The Centers for Disease Control and Prevention (CDC) says “Healthcare-associated infections (HAIs) are a major, yet often preventable, threat to patient safety.”  The healthcare associated infections is of increasing concern to those responsible for patient care in hospitals and other healthcare facilities. It is one reason for the increasing use of antimicrobial additives in medical device applications. Polymers containing effective antimicrobial additives help reduce infection risks in healthcare facilities.

In addressing the need for combating HAIs, a series of antimicrobial polymer compounds have been developed. The technology used incorporates uniformly dispersed antimicrobial additives into the polymer matrix, retaining maximum efficacy over the service life of the medical device.

There are a number of chemical additives with antimicrobial characteristics that can be incorporated or applied onto a polymer surface providing the efficacy required to destroy unwanted pathogens. However, there are only a limited number of affordable additive types available and compatible with a selected polymer type. When it comes to a synthetic elastomer such as synthetic polyisoprene (IR), selection of an appropriate antimicrobial additive can be quite challenging.

Silver is the most widely used antimicrobial additive. However, its use in polymers can drive the materials costs high and yield some undesired features such as discoloration. To avoid these pitfalls, the newly developed antimicrobial polyisoprene contains non-silver antimicrobial additives, which helps keep costs down, while still being compatible with the polymer, processing and cure chemistry. The amount of additive was kept to an acceptable level as to make it non-cytotoxic, yet effective in its antimicrobial properties. Table 1 below shows a couple of examples.

Efficacy as per ISO 22196

These new antimicrobial polyisoprene compounds are as effective as traditional polyisoprene compounds in septums and injection sites for medical fluid transfer applications. The elastic characteristics of polyisoprene provide the desired re-sealability properties of the septum or injection site after piercing multiple times with a needle plus maintain the efficacy of 4+ log reduction when tested per ISO 22196.

As shown in Table 2 below, antimicrobial polyisoprene material RJ687-35 is a 35 durometer material with low compression set, high tear strength and very good elongation. The other 30 durometer material, RJ651-30, shows very good tensile strength, high tear strength, very good elongation and low compression set. These antimicrobial polyisorprene compounds maintain excellent physical and mechanical properties while providing efficacy against common pathogens.

Physical and mechanical properties




Saman Nanayakkara, MSD Engineering Manager




This article was contributed by Saman Nanayakkara, Engineering Manager, Parker Hannifin Composite Sealing Systems Division.




Other related topics:

Medical Polyurethanes for Life Science Applications

Improved Polyisoprene Ideal for Self-Closure Medical Applications

What Qualify as Self-Sealing Septa

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