Infection Control Today: inside central sterile

February 1, 2005

Keeping a Clean Slate
The Effort to Protect Instrumentation from Tough Infectious Agents Such asBiofilm and CJD Prions
By Kris Ellis

The constant battle to guard against thespread of infection and promote patient safety is waged on many fronts in eachand every facility. As front-line participants, sterile processing department(SPD) personnel and infection control practitioners (ICPs) must focus theirattention on variety of different elements, including surgical instruments andmedical devices. Biofilm and Creutzfeldt-Jakob disease (CJD) are two verydifferent threats that have the potential to cause problems for facilities ifthey take up residence on instruments and devices.

Biofilm can be generally defined as a group of microorganismsthat form on a solid surface that comes in contact with water. As theseorganisms grow and multiply, they form a protective layer made up ofpolysaccharides. This layer can make any pathogenic organisms contained in thebiofilm very difficult to eradicate. Biofilms have been implicated in severalinfections, such as bacterial endocarditis and Legionnaires disease, and can be extremely resistant toantibiotics.1

Biofilms are present literally in or on any device thatsees water, says Martin Favero, PhD, director of scientific and clinicalaffairs at Advanced Sterilization Products. The reality is any kind of waterwill support these organisms to a certain extent. When organisms grow in afluid, they tend to attach; they migrate to surfaces, they attach themselves tosurfaces and then cover themselves with the socalled biofilm.

This phenomenon can become a serious concern from an infectioncontrol perspective. The importance is that, with some devices in somesettings, especially those things that get disinfected, the organisms that areembedded in the biofilm, in spite of the fact they might be simple bacteria likepseudomonas, they take on the resistance that often approaches that of abacterial spore because the germicide cannot penetrate the biofilm, Faverocontinues.

Theyre very tenacious and very difficult to get off ofsurgical instruments once they form, says Carla McDermott, RN, CNOR,education specialist, perioperative services, at Clearwater, Fla.-based MortonPlant Mease Hospitals. Its kind of like taking Scotch tape and winding itaround and around itself it gets bigger and bigger the longer its leftunmanaged.

McDermott explains that because biofilm is microscopic, it issometimes difficult to communicate the importance of dealing with it andpreventing it from forming. She points out that an aggressive approach withcleaning materials and tools is a necessity. You have to use a brush to cleanthis stuff, she continues. You have to use the proper mix of chemicals fordisinfection and for the enzyme cleaners. It takes an enzyme cleaner to getthrough this stuff, but it takes physical friction as well its notsomething you can just soak and rinse off; that isnt going to help.

Stringent observance of proper cleaning procedures is the bestdefense against biofilm. Do not skip steps in the cleaning process, says Becki Jenkins, CST, RCST, CRCST, FEL, president and CEOof Sterilization by Design. Follow manufacturers recommendations forcleaning/decontamination of devices to include recommended solutions.

Jenkins explains that certain equipment can be more prone tobiofilm formation. Instruments that are affected the most are lumens that arehard to reach or surfaces that are corrugated or textured and make effectivecleaning difficult, she says. Insulated instruments present a concern whenthe insulation is not properly maintained and can thereby provide a safe havenfor organisms between the insulation and the instrument. When in doubt, yourinstrument repair company can help you and you can send the instrument inquestion for testing.

Devices and instruments are not the only potential sources ofbiofilm. Washers and disinfectors can become colonized with biofilm,which can cause contamination on the instruments, says Stephen Kovach, BS,director of education at Healthmark Industries. Thats why as centralservice departments its important to use a descaler according to theinstrument washer/disinfector manufacturers guidelines.

The use of a washer/decontaminator and/or ultrasonicwashers, depending on the type of instrumentation being cleaned, can beeffective in removing biofilm, says Rudolph Gonzales, RN, MSN, CNOR, CHL,CRCST, manager of the central sterile department at Medical Center of Louisianain New Orleans. Gonzales also points out that inspection for visible bioburdenis vital, as is the use of appropriate soaps and enzymatic cleaners, as well asthorough rinsing.

More complex instruments such as endoscopes may requiredifferent techniques. Ultrasonic cleaning using an enzymatic solution workswell for us on lumened items and for fragile instrumentation, Gonzalescontinues. Cavitation that occurs in this procedure removes miniscule tracesof tissue. Handwashing using enzymatic and instrument company-recommendeddetergents can also provide a reduction of biofilm when the other methods arenot available. Visual inspection throughout the process will ensure thatinstruments are ready for sterilization.

Even when washers are in optimal condition, Jenkins points outthat they alone are not enough. Please, please do not assume that awasher/decontamination unit, though very effective in removal of bioburden, willdo all that needs to be done, she says. Never, NEVER skip steps in thecleaning and decontamination of instruments.

Kovach reiterates that it all starts with effective cleaningpractices. The real part of helping to prevent biofilm is that yourecleaning and making sure youre getting it done as soon as possible and makingsure whether youre doing it manually or its an automated process youre really monitoring it and making sure your equipment and your techniqueis good.

It all comes down to having properly trained and dedicatedSP workers who pay attention to detail, Gonzales says in summary. Allinstruments that come to the SPD are infected with multiple sources forpotential infection bacteria, viruses, protozoa, fungi, spores,antibiotic-resistant bacteria, etc., which require that all personnel usestandard precautions every day for every instrument that is processed.

CJD

CJD, although extremely rare, remains a significant concernfor infection control personnel due to the fact that no treatment currentlyexists for the disease, and the prions that cause it are unusually resistant tostandard decontamination methods.2 This combination can be frightening, asevidenced by recent developments at Atlanta-based Emory University Hospital inwhich the facility notified 98 patients of possible CJD exposure.

Most infectious agents are living microorganisms, which cangenerally be killed by a biocidal substance of some sort. Prions, which areproteins, present a different type of challenge altogether.

When youre talking about a prion, youre talking aboutquite a different entity an infectious protein, says Peter Burke, PhD,senior vice president and chief technology officer at STERIS Corporation. Weall have prions in our body that are normal, that cause us no harm;

something triggers a prion protein to become an infectiousprotein with abnormal structure, and that infectious prion has the ability toact like a chaperone protein that induces normal prion proteins to bebecome abnormal and infectious.

Burke notes that a prions basic chemical properties make itvery difficult to eradicate. Let me give you a simple analogy, he says. When you cook something in a pan, during the cookingprocess you have lipids and proteins, and you have a variety of other types ofmatter. As you cook, you can fix that to the surface. Were all aware of howhard it is to get that off after cooking. In a hospital setting, when you letsomething dry, it has the ability to affix itself to a surface and it then hasthe tendency to be harder to remove.

Burke explains that prions that have affixed themselves ontoinstruments will develop a greater affinity to that surface if they are notloosened in some way early on. Coupled with that is the fact that when younow treat them with cleaning agents and processes, the theory that mostscientists believe is the case for prions is that the surface prions (and othermaterials) will become inactivated or removed and the ones that are hidden belowor remain on the surface afterward are still infectious and can transmitdisease, he continues.

There are a number of guidelines and recommendations fromvarious associations, such as the World Health Organization (WHO),3 regardingthe disinfection of instruments that may house CJD prions. Oftentimes, themethods recommended are harsh and have the potential to damage fragileinstrumentation. The specific procedures employed by different facilities mayvary depending on their own unique circumstances, but basic precautions do existthat may be employed at any facility.

I think its very important that in most cases, hospitalswill not know whether a person has one of these prion diseases, says GeraldMcDonnell, BS, PhD, senior director of technical affairs at STERIS. CJD and other similar infections develop very slowly, andpatients may not know they have been infected or carry the disease for a longtime. This means that procedures could be performed and instruments used on apatient without knowing that the patient is infected. This is why universalprecautions are recommended to avoid possible infection.

McDonnell describes these precautions as follows:

  • Keep instruments moist

  • Perform adequate cleaning to physically remove as much soilas possible

  • Use cleaning chemicals that are effective at inactivating prions

  • Use prolonged steam sterilization cycles

In the United States, I thinkpeople would tend to agree with Bill Rutala, says Favero. Basically whathe recommends, and this will be reflected in the CDC guidelines on disinfectionand sterilization once theyre published, the way they will read is unless youhave three things going on, you really dont have to use a special protocol.The three things are, one: you have a patient who is either known or suspectedto have prion disease. Secondly, the instruments in question are exposed tohigh-risk tissue such as brain tissue. Third, that the instrument be a criticalinstrument, which it would be automatically if it was a surgical instrument.

If those three conditions are present, deviation from normalsterilization protocol is recommended in favor of methods such as extended steamsterilization cycles and the use of sodium hydroxide. Favero adds that severalrecent publications have indicated that certain alkaline cleaners may also havepotential in combating prions. I think this is good because I think thescientific community has finally combined prion sciences with disinfection andsterilization sciences, he says. Prior to this time, a lot of the prionscientists basically were not using the correct protocols for establishingwhether or not a certain procedure could inactivate prions. I think weve turned a corner on that.

The harshness of the WHO-recommended treatment methodsprompted STERIS to embark upon research in the area and eventually organize astudy exploring methods of disinfecting prion-contaminated devices.4 Therewas a lack of qualified, complete studies on prion inactivation that wereperformed under laboratory control; STERIS undertook to conduct such a study,says Burke. The WHOrecommended treatments were used as positive controls,including sodium hydroxide, bleach and high-temperature treatment. In addition,new potential prion treatments were evaluated in comparison to the recommendedWHO guideline treatments.

McDonnell notes that the purpose of the study was two-fold: toestablish a methodology for testing prion inactivation, and to test existing anddeveloping treatments using this methodology in a scientific, controlled manner.

Results of the study supported the efficacy of current WHOguidelines, but also noted potential drawbacks. The treatments recommended bythe WHO did work to inactivate prions, although they were harsh for instrumentsurfaces and users, says McDonnell. However, autoclaving at 134 degrees Fahrenheit underrecommended WHO conditions did not result in total inactivation.

The study also found that three milder methods of disinfectionincluding a phenolic disinfectant, an alkaline cleaner, and the combinationof an enzymatic cleaner and vaporized hydrogen peroxide (VHP) were also effective.5

Sorting through the wealth of information addressingdisinfection and sterilization products and methods can become overwhelming, butJenkins points out that adherence to established policies and procedures bywell-trained personnel is the bottom line. The issue is in central sterileitself and whether or not there are certified or non-certified professionals,she says. In addition, it is critical that no step of the process be skipped,modified, shortened or otherwise manipulated to appease the push for fasterturnover or a rush case in the operating room. The consequences could be costlyand devastating to patients and their families. Stand up for the rights ofpatients first, surgeon preference second and convenience dead last, if at all.