Hospital Acquired Infection (HAI’s) and Surgical Site Infection (SSI’s)
According to the January 2009 HHS Report, “Hospital Acquired Infection is the 4th largest cause of death with a higher mortality rate than AIDS, breast cancer, and automobile accidents combined.” This fact was a highly guarded secret by the healthcare community until recent state legislation was passed that now forces hospitals in 27 states to report their infection rates to the state. Imagine the number of people who might not have elective surgery if they were aware of their one in five chance of contracting a surgical site infection while in the hospital.
The consequences of such an infection while in the hospital range from:
- Increased hospital stay
- IV Antibiotics
- Lifetime oral antibiotics
- Revision surgery
- Return visits
- Amputation
- Death
| Date | Publication | Title |
|---|---|---|
| Current | Hospital Compare | Hospital Infection Statistics |
| 2012 | Associated Press | Medicare fines over hospitals’ readmitted patients |
| 3rd Edition | Journal of Hospital Infection | Surgical site infections: how high are the costs? |
| 2012 | The Washington Post | NIH superbug claims 7th victim |
| 2012 | Journal of the American Academy of Orthopaedic Surgeons | Contributing factors to surgical site infections. |
| 2012 | Ventura County Star | Simi Valley Hospital fined by state for surgery |
| 2012 | NY Daily News | Texas boy 7 who contracted rash and died in San Diego area was killed by flesh-eating bacteria: autopsy |
| 2001 | Emerging Infectious Diseases | Biofilms and Device-Associated Infections |
The Costs of Infection
Recent Health and Human Services (HHS) estimates place the annual costs of HAI’s at around $30 billion in the US alone. Post-operative costs for a single incidence of infection can be as much as $100,000. These costs are a tremendous burden for Medicare, private insurers and hospitals. In October 2008, HHS implemented new policies which will NOT pay or reimburse hospitals for the treatment of HAIs or SSIs. Given the financial pressure already on hospitals and surgeons, this mandate could potentially put some hospitals out of business altogether. It will also send hospitals and surgeons clamoring to find post-operative solutions such as self-sterilizing implants and medical devices, in addition to better hospital cleaning protocols.
| Date | Publication | Title |
|---|---|---|
| Current | Hospital Compare | Hospital Infection Statistics |
| 3rd Edition | RID | Unnecessary Deaths: The Human and Financial Costs of Hospital Infections |
| 2012 | Surgical infections. | Adherence to Surgical Care Improvement Project Measures and Post-Operative Surgical Site Infections. |
| 2012 | Surgical infections. | Length of Stay and Cost for Surgical Site Infection after Abdominal and Cardiac Surgery in Japanese Hospitals: Multi-Center Surveillance. |
| 2012 | AzCapitolTimes.com | ‘Obamacare’ ailing economy rising costs lead to health care revolution |
| 2009 | Spine. | Incidence prevalence and analysis of risk factors for surgical site infection following adult spinal surgery. |
| 2004 | Infectious Diseases Society of America | Bad Bugs – No Drugs: As Antibiotic Discovery Stagnates…A Public Health Crisis Brews |
Antibiotic Resistant Bacteria
In recent years, bacteria which are resistant to antibiotics have begun to proliferate. The most well-known antibiotic resistant bacteria is probably Methicillin-resistant Staphylococcus aureus (MRSA). There are several different variants of MRSA: the best known being hospital acquired MRSA and community acquired MRSA.
It is not safe to assume that the ease with which device related infections can be treated will remain static. A study was published in 2005 that reviewed a consecutive series of patients who underwent revision hip or knee arthroplasties due to bacterial infection at PamelaYoude Nethersole Eastern Hospital in Hong Kong between 1995 and 2003. None of the bacteria isolated from 1995 to 1996 were multiple-drug resistant. Subsequently, however, from 1997 –2003, most of the isolates were multiple-drug resistant, with MRSA being the most common. Half of the isolates of Staphylococcus epidermidis and Escherichia coli demonstrated multiple-drug resistance. Treatments which would have been effective during earlier years would likely have failed on the infections in recent years.
| Date | Publication | Title |
|---|---|---|
| Current | Hospital Compare | Hospital Infection Statistics |
| 2012 | news.com.au | Doctor detectives stop killer superbug KPC Klebsiella pneumoniae at NIH |
| 2011 | ADR Support | Why Am I Still Sick? – Trailer V1 |
| 2010 | The New York Times | Rising Threat of Infections Unfazed by Antibiotics |
| 2005 | Journal of orthopaedic surgery (Hong Kong) | Implications of the changing pattern of bacterial infections following total joint replacements. |
Silver – A Broad Spectrum Antimicrobial
Silver has a long history of safe use as an antimicrobial agent. The Romans used silver coins to preserve their casks of wine. The Soyuz and Apollo spacecraft used silver as a component of their water purification systems. Silver nitrate has been used as eye drops for new born infants to control eye infections. Due to its broad spectrum of action (ability to control over 600 microorganisms), Silver has even been used as a component of silver sulphadiene, proving superior to conventional antibiotics for the treatment of burns. Silver has been shown to reach levels as high as 75 ppb in the blood of burn victims without adverse effects. Likewise, levels as high as of 120 ppb silver in drinking water are recognized as safer for human consumption.
Because the mode of action of silver as an antimicrobial is at least trimodal, it is extremely unlikely that resistant bacteria will easily develop.
It will not cause significant damage to mammalian eucaryotic cells below 1 ppm. Hence it has found significant use in wound dressings, burns treatment, catheters and dental fillings. On the other hand, it can also be toxic to microorganisms and procaryotic cells – becoming lethal at levels as low as 20 ppb.
| Date | Publication | Title |
|---|---|---|
| Current | Hospital Compare | Hospital Infection Statistics |
| Current | Wikipedia | Medical uses of silver |
| 2010 | Microbe Wiki | Silver as an Antimicrobial Agent |
| 2009 | International Journal of Antimicrobial Agents | The growing importance of materials that prevent microbial adhesion: antimicrobial effect of medical devices containing silver. |
| 2007 | Surgical Neurology | Do silver-impregnated dressings limit infections after lumbar laminectomy with instrumented fusion? |
| 2006 | Journal of Medical Microbiology | Antimicrobial activities of silver dressings: an in vitro comparison |
| 2002 | Journal of Wound Care | Silver I: its antibacterial properties and mechanism of action |
Instrumented Orthopedic Surgery is a Relatively Recent Innovation
Instrumented orthopedic surgery involves the implantation of metal, ceramic and plastic materials into the human body to reconstruct and support damaged and defective elements of the human skeleton. The most common procedures include spinal repair using spinal implants and fixtures (including plates, rods and screws) to fuse and reposition discs that are damaged or out of alignment. Other examples of instrumented orthopedic surgery include hip, knee and shoulder replacement. Such procedures have been highly successful in restoring the quality of life for patients who had been disabled or seriously injured. Full mobility is generally restored, often along with complete relief from chronic pain.
The Formation of Biofilms
When as little as a few bacteria aggregate on a susceptible surface, they can communicate through a mechanism called quorum sensing and can form a diversified efficient ecosystem that allows the bacteria to thrive and proliferate. Such films which can occur on many surfaces are called biofilms. Bacteria within biofilms assume various roles with differentiated functions. They secrete a glycocalyx or carbohydrate polymer which adheres strongly to the surface and binds the bacteria to it. This film is difficult to remove and difficult for antibiotics to penetrate. Because of the nature of biofilms, they are ideal environments for microorganisms to develop resistance to antibiotics. Furthermore when bacteria become mature and reproduce, they produce daughter cells which are less hydrophobic. These daughter cells break away from the biofilm to form planktonic bacteria which are released into the circulatory system. They roam freely, seeking new sites of attachment and, as they become more mature, they can adhere to heart valves or deposit into other organs where causing serious or fatal systemic infections becomes a likely threat. The natural properties and role of bacterial biofilms in promoting device related infections have been reviewed by Donlan.
| Date | Publication | Title |
|---|---|---|
| Current | Hospital Compare | Hospital Infection Statistics |
| Current | Stanford.edu | Biofilm Studies |
| 2011 | Medical News Today | Biofilms On Medical Devices Can Be Produced By One Species Of Pathogen |
| 2009 | TED Talk | Bonnie Bassler: How bacteria “talk” |
| 2009 | Springer | The Role of Biofilms in Device-Related Infections |
| 2002 | Emerging Infectious Diseases | Biofilms: Microbial Life on Surfaces |
| 2001 | Emerging Infectious Diseases | Biofilms and Device-Associated Infections |
| 1999 | Science | Bacterial biofilms: A common cause of persistent infections |
A Significant Risk Involved With Instrumented Procedures.
The materials being implanted are metals or man-made materials that are of significantly different structure, composition and surface characteristics than make-up of the human body. The tissues within the body are in a constant state of flux with cells being turned over constantly, while being protected from infection by an active, vigilant immune system.
Currently, implanted materials composed of metals such as stainless steel and polymers like polyetherether ketone (PEEK) provide hard, inert surfaces within the body which are more hydrophobic than the natural surfaces in the body and possess no mechanism of protection. Since PEEK is inert and uncharged, it does not integrate well with human tissue. A fibrous layer of tissue builds up around the PEEK implant, leaving an open and unnatural hydrophobic interface at the surface of the implant. Osseointegration and tissue integration have been shown to be poor. The open hydrophobic interfaces of inter-body implants have proven ideal environments for the attachment and proliferation of bacteria. Planktonic bacteria – which may be circulating at a low level in body fluids or inadvertently be introduced into the surgical site during surgery – are attracted to hydrophobic surfaces and attach readily to the implant surface. With little competition from benign bacteria and a rich nutrient source, pathogenic bacteria can rapidly proliferate here.
| Date | Publication | Title |
|---|---|---|
| 2010 | Southern Medical Journal | Postoperative instrumented spine infections: a retrospective review. |
| 2001 | Journal of orthopaedic trauma | Postoperative wound infection after instrumentation of thoracic and lumbar fractures. |
| 1997 | Clinical infectious diseases: an official publication of the Infectious Diseases Society of America | Wound infections following spinal fusion with posterior segmental spinal instrumentation. |
Treatment and Consequences of Device Related Infections
There are three courses of action for a surgeon when an interbody device becomes infected.
- The patient can be put on a course of intravenous antibiotics with hopes that it will eliminate the infection. This approach is not always effective since the biofilm exerts a protective effect, and antibiotic resistant bacteria may be present or can rapidly develop.
- The next course of action involves re-opening the surgical site, de-briding the implant and flushing the site with disinfectant or antibiotic and hoping that the infection will be controlled.
- In cases where the first two procedures fail to control the infection, it will be necessary to excise the implant and clean the site of the operation as thoroughly as possible.
In cases where the infections get out of control morbidity or mortality may ensue.
| Date | Publication | Title |
|---|---|---|
| 2012 | Journal of neurosurgery. Spine. | Factors influencing 2-year health care costs in patients undergoing revision lumbar fusion procedures. |
| 2012 | Clinical Infectious Diseases | New Developments in Diagnosis and Treatment of Infection in Orthopedic Implants |
| 2009 | Economist | The Direct Medical Costs of Healthcare-Associated Infections in U.S. Hospitals and the Benefits of Prevention |
| Date | Publication | Title |
|---|---|---|
| Current | Hospital Compare | Hospital Infection Statistics |
The Search for a Solution
Infections involving surgical implants has been described as “The great unsolved problem of the last decade.”
Several approaches have been explored over the past decade to help reduced the level of infections associated with instrumented orthopedic surgery and caused by the growth and proliferation of biofilms on their susceptible surfaces.
Soluble coatings of antibiotics have proven ineffective because their delivery is not sustained, and the interaction of antibiotics with bacteria embedded in biofilms very likely contribute to the development of antibiotic resistant variants – due to the concentration gradients involved and the bacteria that exist in the biofilms at various stages of dormancy.
Surface coatings on devices are not suitable because in the harsh environment of body fluids, such as blood, and under the mechanical strain which the implants must endure, the coatings can become de-laminated and cause serious complications within the circulatory system as mobile particulate matter.
A Stable Self-Sterilizing Material
It has now been found possible to quantitatively deliver silver and other antimicrobial metal ions from an ion exchange medium actually embedded in an implant material such as PEEK. Since the ion exchange medium (an alumino silicate cage like material) is physically embedded in the PEEK polymer, there is no danger of de-lamination or release of particulate matter into the circulatory system. Because of the nature of the silver, or metal zeolite, and its interaction with physiological fluids, it is possible to accurately release precisely controlled levels of the metal ions over long periods of time. A recent study carried out in Germany has shown that catheters which incorporated silver zeolite were able to control and inhibit the formation of biofilm on the surfaces of the catheter for up to 28 days. The controls, which did not contain silver zeolite, showed significant levels of infection.
DiFUSION’s CleanFUZE™ Technology
The CleanFUZE™ biomaterial consists of a composite material produced by incorporating metal zeolite powders, which are stable up to 600 C into PEEK polymer and melt at about 400 C.
The material can be injection molded or extruded and machined into shapes which are suitable for use as orthopedic implants. The material can also be used to encapsulate or powder coat metal structures that would otherwise have imperfect compatibility with human tissue.
When the CleanFUZE™ material comes into contact with electrolyte solutions such as body fluids, the surfaces of the exposed metal zeolites present in the surface of the implant will be bombarded with anions such as sodium potassium and calcium, and silver ions will be released in exchange. When microorganisms present on – or alighting on the surface of the implant – encounter silver cation levels between 20 and 400 ppb, they will be rapidly destroyed. These organisms that typically can easily form a biofilm on the surface of a material such as plain PEEK will not survive long enough to initiate biofilm formation as the surface will be protected.
Since the surface of the implant contains significant quantities of exposed zeolite, it should be much more susceptible to interaction and integration with the host tissue. If proper integration takes place, a fibrous layer will not form around the implant and an open interface should cease to exist quite quickly. With the potential of zeolite to carry various therapeutic ions, it should be possible to develop systems which exhibit pro-healing and anti-inflammatory effects – thus promoting much more rapid healing that would be the case with conventional inert implants.
*CleanFUZE™ is not FDA approved for sale in the U.S.*
