It's highly unlikely to go more than a day without hearing about Methicillin-resistant Staphylococcus aureus or the (MRSA) "superbug" as it has been dubbed, given all the media attention it has received of late. The deadly strain has become uber-resistant to antibiotics — and is transmitted mostly in hospital settings.
MRSA along with other infections garnered from hospital settings are the fourth leading cause of death in the U.S., which cost an average of $57,000 per patient for diagnosis and treatment and can cost hospitals between $28 billion and $30 billion annually in extended care and treatment, according to the Centers for Disease Control.
But the seeds to preventing the spread of these diseases in clinical settings, lies with a treatment from the past — silver. Historically silver has been used as a bacteria killer for as far back as ancient Rome. It was used to preserve foods and heal wounds. In the 1800s it was used to treat skin ulcers. However the use of antimicrobial silver was supplanted by antibiotics — which gave way to recent strains of bacteria that were resistant to current treatments.
"Silver has been shown to be resistant to just about everything," David Rardin, VP Marketing and Development of Acrymed (Portland) told Medical Device Daily.
The problem with most devices, particularly catheters and endo-trachial tubes or anything that would stay in the body for a period of time is that bacteria colonies form on the device.
Ionic silver has become a favored substance for surface modification for several reasons: It has broad spectrum antimicrobial action; it's well-tolerated by tissue; it is compatible with most materials used in making medical devices; it can be compounded into the submatrix or applied on the surface; and resistance to it is largely non-existent.
Acrymed's Silvagard are nanoparticles that are formed chemically in a solution, which are uniform in size (10 nm) and do not agglomerate to form large particles, but stay in suspension pending application to materials.
It is neither a direct incorporation into the materials used nor a surface coating. It relies on discrete silver nanoparticles deposited uniformly but discontinuously on the submicroscopic and nearly molecular level onto the surface of the devices after they are manufactured.
After the Silvagard solution is prepared the device is then dipped in the solution. The adhesion to the device is such that that this sliver treatment can't be removed by ultrasonic cleaning, the company said. Silvergard also adheres to elastic devices when they are stretched or flexed.
"Our technology inhibits the formations of these bacteria or these colonies on the device," Rardin said.
So are Acrymed's claims about Silvagard a definitive answer to preventing further spread of the MRSA strain and other hospital bacteria infections?
"Definitely," Rardin said. "It's just a matter of getting the technology out there. The FDA approvals actually come with the devices themselves."
In July the FDA issued a proposed guidance document on antimicrobial device submissions stating that when companies claim their product reduces or prevents device-related infections, the claim should be supported by such clinical data.
Specifically, it's a matter of the devices receiving FDA approval coupled with the Silvagard coating and other applications in a timely manner. So the question becomes will med-tech companies catch on quick enough?
Baxter Healthcare (Deerfield, Illinois) which uses the Silvagard solution has seen the light. The company said late last week that it had received 510(k) clearance from the. FDA for its V-Link Luer-activated device (LAD) with VitalShield protective coating. V-Link with VitalShield is the first needleless IV connector containing an antimicrobial coating. Baxter said it will launch the V-Link device with VitalShield coating in the U.S. starting in the first half of 2008.
"We're getting calls everyday about Silvagard," he said. "Medical devices are looking more toward ways to reduce these infections."
But Acrymed isn't the only game in town when it comes to applying silver to medical device applications.
In the last few months, companies have sent a plethora of releases reporting on applications that could coat medical devices with silver. In its June issue, MDD's sister publication Biomedical Business & Technology named up to 16 companies using silver for antimicrobial protection in wound dressings.
If a new list was taken then that amount would probably double.
Some of the latest companies to throw their hats in the fire against MRSA and hospital infections include:
Pure Bioscience (San Diego) and its silver dihydrogen citrate, which is an electrolytically generated source of stabilized ionic silver. The bacteria views the molecule as a food source and once the organism consumes it, SDC destroys the bacteria by disabling proteins and halting its metabolic and reproductive functions.
C.R. Bard (Murray Hill, New Jersey) recently received FDA clearance for the Agento endotracheal tube, which is coated with a thin layer of silver.
"Patients who require ventilator support are at increased risk for pneumonia, which poses a significant public health issue. This product can help to lower the risk," said Daniel Schultz, MD, director of FDA's Center for Devices and Radiological Health.
Bacteria infections in hospitals have been drawing more attention than ever — especially with the advent of the MRSA strain.
A large study led by the CDC and published in the Oct. 17, 2007 issue of the Journal of the American Medical Association estimated that MRSA would have been responsible for 94,360 serious infections and associated with 18,650 hospital stay-related deaths in the U.S. in 2005. These figures would make MRSA infection responsible for more deaths in the U.S. each year than AIDS.