What Are Antimicrobial Materials For Plastic Injection Molding?

By Rena Ivory, Crescent Industries, Inc.

When antimicrobial materials are used in plastic injection molding for medical device components, the reduction in infection is significant and measurable.

Healthcare acquired infections are known as HAI's within the industry. The statistics for these incidences have caused alarm in some medical communities.

Tracking the reduction of health device induced infections is a standard part of the process - and serves to help highlight when a change such as the addition of antimicrobial materials to the medical device manufacturing process is really working.

Antimicrobial Material Performance within Plastic Injection Molding Processes

For decades it has been a common practice to rate the impact of healthcare acquired infections tracked by the CDC in the U.S., and by similar organizations around the world.

A focus for preventing these infections gathered significant momentum by July of 2008. The Steering Committee for the Prevention of Healthcare-Associated Infections was created under the U.S. Department of Health and Human Services (HHS).

The group released an initial action plan in 2009, which made its focus on prevention in acute care hospitals, then ambulatory surgical centers, then end-stage renal disease hospitals.

In April 2011, HHS launched a goal of decreasing HAIs by 40% compared with 2010 rates, with 1.8 million fewer injuries to patients and more than 60,000 lives saved over the next three years. Ten strategies were developed and implemented - designed to eventually end all HAI's. These include engagement with:

• Frontline clinicians
• Healthcare executives
• Healthcare administrators
• Clinical leaders
• Healthcare Advocates
• The government

Among these strategies are those that focus on research, reporting, and metrics and the tools to support them; outreach and education, incentives and oversight.

Materials for Building the Strong Antimicrobial Performance

Design features and inherent material properties are required in the most invasive devices, which deliver their own sets of difficulties for minimizing infection risk.

Most devices are utilizing an inherent antimicrobial material approach to provide added performance in a manner that addresses infection risks to patients. Devices like in-dwelling urinary or vascular access catheters, IV components, wound dressings, medical equipment, and implantable devices, all are currently marketed as containing properties to minimize the risk of infection.

These products will employ one or more active microbial species. This is either a coating or within the matrix of the material. This then leaches onto the device surface to help prevent microbe colonization or bio-film formation.

This active prevention of bio-film formation is key for the performance objective with antimicrobial medical devices. If the bio-film doesn't form, the treatment options are more severe and costly, which come with additional risks to the patient.

Silver additives deliver antimicrobial activity to materials with strong performance at relatively low concentrations means it is low in human toxicities, and has an ability to migrate in sufficient concentrations to the surface. Silver is widely used and is known to kill over 99.99% of bacteria within 24 hours of contact. It remains effective over the lifetime of the product.

This antimicrobial additive is for compounded thermoplastic materials. Other metals and organics are also being used. Some of these include a copper-alloy for plastic surface coatings.

Newly advanced polymers are also being made with antimicrobial agents embedded in the resin itself. The exposed surface is always a deadly place for bacteria. The antimicrobial compound is added during the manufacture of the resin. There is no alteration of the physical or thermal properties of the resin—which remains highly suitable for plastic injection molding.

Antimicrobial resins have been developed than can kill the most deadly infections, including MRSA, a most resistant and potentially deadly bacterial infection often found in hospitals.