Infection Control Today - 04/2004: Raising the Bar on Disinfectant Testing

April 1, 2004

Raising the Bar on Disinfectant Testing Is It Needed? Experts Disagree

Raising the Bar on Disinfectant Testing
Is It Needed? Experts Disagree

By Gail Stout-Flower

Disinfectants are a standard method for treating non-criticalenvironmental surfaces. Claims of efficacy for any specific pathogen must be testedunder laboratory conditions to make sure the formula does what it claims to do.Then, each claim must be reviewed and approved by the EPA before it can be onthe product label. This testing must be done per EPAapproved standards, whichcurrently require efficacy under a 5 percent organic soil at 200 ppm to 400 ppmhard water.

It seems that testing disinfectant claims under high soil loadand very hard water (i.e., real world conditions) would be the nextlogical step to see if a product works under the stresses of existing conditionsin situations where surface pre-cleaning may be less controlled. This has been done with one product to date, and surely morewill follow. To what extent this type of testing adds to the overall benefitsderived by the user is a subject that draws polarized opinions.

From the Germs Perspective

Today, the entire globe has been reduced to a simple roadmap.This is good for the global economy and is also a boost for the globaltransmission of infectious pathogens. One only has to look at the recentepidemics in various global areas of SARS, influenza, monkeypox, avian flu, hoofand mouth disease and illnesses that have caused popular cruise lines to turnback to port, to grasp how fast and thoroughly any disease has the potential towreak havoc.

Aside from imported diseases, there are plenty to deal with inthe U.S. The medical institution recognizes the fact that many are evolving intovery antibiotic resistant strains, making them harder to cure.

Ali M. Javadian, PhD, MPH, manager of technology developmentat Wyeth Vaccines Research in Pearl River, N.Y., is in charge of all technologyregarding immunology at that facility. He is adamant about the necessity ofinfection prevention, saying, The emphasis must first be on prevention of thespread of infectious diseases and then on the cure.

Disinfection Basics

In his recent paper, Surface Disinfection: Should We Do It?,William A. Rutala, PhD, MPH, Division of Infectious Diseases at the Universityof North Carolina School of Medicine writes, Viruses can be acquired fromenvironmental surfaces either directly from surfaceto- finger-to-mouth ordirectly from surface-to-mouth.

Chemical disinfection of contaminated environmental surfaceshas been shown to interrupt transfer of rhinovirus from these surfaces tohands.1 In experimental studies, the use of disinfectants has been shown to bean efficient method of inhibiting the transmission of rotavirus to human subjects.2

Loretta Litz Fauerbach, MS, CIC, practice guidance team leaderfor the Association for Professionals in Infection Control and Epidemiology(APIC), and director of infection control at Shands Hospital, University ofFlorida in Gainesville, concurs, adding, Surface disinfection is especiallyimportant when the pathogen is spread via the contact route...when a susceptibleperson is exposed by touching a contaminated object. Not all exposures lead todisease. Some result in contamination of the hands that can then transfer theorganism to a susceptible individual if hands are not decontaminated via washingor the use of an alcohol hand gel. In this context surface disinfection becomesimportant as a reservoir for acquiring the organism, which then can either betransferred via the hands to someone else or infect the person who is directlyexposed.

Prevention of the spread of infection is paramount nomatter what location, global setting, at home, at work or in our leisuresettings, says Paulette Marquardt, RN, central service supervisor at MayoClinic Hospital in Phoenix. The outbreak of disease can be transmitted aroundthe world in an incredibly short time. Objects need to be cleaned to remove allforeign material from the surfaces before disinfection can be accomplished. According to APIC, a disinfectant is a germicide thatinactivates virtually all recognized pathogenic microorganisms but notnecessarily all microbial forms. Surface disinfectants are used on allenvironmental surfaces in a hospital setting. This is only one method ofpreventing the spread of infection. Equally as important to break the chain oftransmission is handwashing.

From a global perspective, Stuart Reid, professor ofcomparative epidemiology and informatics at the Universities of Glasgow andStrathclyde in Glasgow, U.K., states that disinfectants do play a serious rolein the reduction of disease transmission, both directly through biocidalactivity and reduced load and also indirectly through general increasedstandards of hygiene.

Matthew J. Arduino, MS, PhD, supervisory researchmicrobiologist, Epidemiology and Laboratory Branch in the Division of HealthcareQuality Promotion at the Centers for Disease Control and Prevention (CDC) inAtlanta, puts the whole picture into perspective. What is the actual role of surface disinfecting as relatedto retarding the spread of bacterial, viral and fungal infectious agents inhospital settings? The answers to these questions must first be prefaced with ashort review of the chain of infection. For infection to occur, all five linksin the chain must be operational. These links are: a) a susceptible host; b) anagent in sufficient numbers (i.e., dose); c) virulence of the agent; d) mode oftransmission; and e) portal of entry.

Environmental surfaces may serve as a reservoir ofmicroorganisms, he adds. Organisms present on these surfaces can betransferred from the surface to a person via hand contact or contact with anobject that has touched the environmental surface. This transferal by itself isnot enough to result in infection; the organisms must enter the body through aportal of entry (e.g., mouth, eyes, nose, mucous membranes, or break in theskin). Surfaces that are touched frequently by hand during healthcare (e.g.,equipment handles and knobs, door knobs, light fixtures and bed rails) arepotentially associated with this microbial transfer more frequently compared tothat for the floors and walls. Surfaces that do not make contact with the skinof patients, healthcare staff, and visitors (e.g., floors and walls) should bekept clean. Routine disinfection of these surfaces is not warranted, butdisinfection may be needed if the surface has been contaminated with a bodysubstance or fluid. Frequently touched surfaces, because of their increasedpotential involvement with hand-transfer of microorganisms, should be cleanedand disinfected on a regular basis. The purpose of cleaning and disinfectingenvironmental surfaces is to reduce the numbers of microorganisms on thosesurfaces. Cleaning and disinfecting helps to eliminate or at least minimize thepotential for the surface to serve as a microbial reservoir.

So experts agree, both stringent cleanliness and the use ofdisinfectants are deemed effective methods to stem this unseen microbial attack.All disinfectants state that they are to be used on pre-cleaned surfaces,because too high an organic soil load reduces the efficacy of these products. Sothe question becomes, how clean is clean?

Taking Disinfectant Testing to the Next Level

EPA regulations create a fair playing field across alldisinfectant products; however, it also allows any company to raise the testlevel above the standard. The Environmental Protection Agency (EPA) onlyrequires that laboratory testing be proven to the agencys satisfaction. They will, and have, issued label claims of efficacy underhigh organic soil-load conditions.

When an animal or human bleeds or issues forth other bodilyfluids, these bodily fluids do not self-dilute as they cover a surface. Cancleaning to a 5 percent organic soil level always be enough? One disinfectantmanufacturer set out to test their products for efficacy against known pathogensunder real world conditions: organic soil load of 98 percent and hard water level of 780ppm. Their reasoning being that there are circumstances where it would beimpossible to know the soil load after pre-cleaning and, therefore, theinfectious microbial density in that residual soil.

Robert Prince, president of West Caldwell, N.J.-basedMicrogen, Inc., a microbiological surface chemical distribution network, says,We aggressively pursue testing to simulate the most demanding use ofconditions for our products to ensure their effectiveness in actual healthcaresituations. Ideally, products should be effective in 100 percent organic soilloads, since the current 5 percent organic soil testing requirement is seldomapplicable to real-world situations.

Microgens lab scientists routinely test the companysdisinfectants against a high organic soil challenge of gram negative andgram-positive bacteria as well as enveloped and non-enveloped viruses. Recently,we completed the successful disinfectant testing of D-125 in 98 percent soil andin 791 ppm hard water against Salmonella choleraesuis ATCC 10708 and Staphylococcusaureus ATCC 6538. This is the first EPA approval of a disinfectant usingsuch a high organic soil load for testing data.

Vladis Goncarvos, regulatory affairs manager, ResearchInternational, has a positive opinion, saying, This new claim will probablyset a new standard in the industry. Hospitals are going to find this useful inareas where there may be more than just a little dirt. Just because a product istested at 5 or 10 percent does not mean it wont work at higher levels ofcontamination and should be tested. It will raise the bar for disinfectants byproviding more confidence. Surfaces are precleaned before being disinfected, buthow do they guarantee that the soil remaining on the surface is only 5 or 10 percent? You cant see it. Better to be safe than sorry?

Cuyahoga Falls, Ohio-based Ultronics Inc. manufacturesdisinfectants systems for salons, spas and barbershops. The companys mission is to offer optimum protection forsalon personnel and clients. Infection control standards in the beauty andbarber industry have been upgraded in most states to reflect the new CDCguidelines that were issued in June 2003, says general manager GerriCevetillo-Tuccillo. Two of the organizations that have been diligent infollowing CDC recommendations are the National Interstate Council of StateCosmetology Boards and the National Association of Barber Boards of America.

Recent breakthroughs in the testing of disinfectants undera heavy organic soil load and in hard water conditions reinforces the efforts ofthese governing agencies by offering solutions to regional problems (hardwater), Cevetillo adds. It also further ensures the effectivenessof the disinfectants used in the salon setting, since all of the implements thatare used are exposed to organic and cellular material (hair, nails and skin).Most implements are not pre-cleaned before disinfection, due to time constraintsand poor habits. The ability to accomplish both cleaning and disinfection in onestep is practical and far more protective.

And to consider other areas of exposure, Ali Javadian, PhD,states, When I hear about testing these products in 95-98 percent organicsoil load, I think of facilities where there is a lot of blood, whether human oranimal in veterinary hospitals. When surfaces are cleaned initially, who is tosay what the actual residue soil load is on the surface? EPA standards I believestate that the acceptable test for efficacy against any pathogen is at a 5percent organic soil load. So I think, can you tell in some way that you havewiped up 95 percent of them before disinfecting the surface? It sounds rather inadequate to me.

Rutala adds some validity to the need for disinfection in highsoil load when he writes, Disinfectants are needed for surfaces contaminatedby blood and other potentially infective materials (OPIM). In the U.S., in orderto comply with the Occupational Safety and Health Administration (OSHA) rule onbloodborne pathogens, a blood spill must be cleaned using a disinfectant. Thecompliance directive states that the blood should be disinfected using anEPA-registered hospital disinfectant, a disinfectant with a HBV/HIV claim, or asolution of 5.25 percent sodium hypochlorite (household bleach) diluted between1:10 and 1:100 with water.3 A study demonstrated that in the presence of bloodspills, a 1:10 final dilution of bleach should be used to inactivate bloodborneviruses.4 Even at this concentration, complete inactivation cannot be assured.

Philip Tierno, PhD, director of clinical microbiology andimmunology at New York University Medical Center, adds, There are manyreasons why you would want a germicide that would function in a waterenvironment that may not be in the best chemical condition ... with minerals.Another thing, in regards to the soil bio load, many germicides are inactivatedby heavy soilage. So one that can sustain its efficacy during intrusion by soilwould be an advantageous product just by definition.

Rodney Stine, with OSHA Review in Sacramento, Calif., servicesthe dental area. He adds, My position is that nobody should use anything thatis not approved by the EPA. What they use should be labeled for that purpose,that function, that specific pathogen. The most important thing aboutdisinfectants is their ability to be effective whenever you have large amountsof organic soil because busy staff members usually use the disinfectant as thecleaning media.

Medical facilities have a strict regimen of cleanliness. Therefore, the benefits of testing disinfectants for efficacyunder dirty conditions are often seen as debatable. The point is, medical facilities seldom achieve their ownstandard of cleanliness. For example, hospitals have high standards for whenstaff must wash their hands, but study after study has shown that onlyapproximately 35 percent meet that standard.

Loretta Fauerbach points out, Infection controlprofessionals teach that disinfectants are to be used according to themanufacturers directions at the appropriate use dilution. So if the userfollowed the directions to remove the organic load prior to disinfection, thereshould be no problem. However, this is the precise problem. Busy staff willnot always read labels carefully. Often non-English speaking personnel use the disinfectants,though their reading of the printed information on the bottle may be limited.Using a cleanser/disinfectant rather than relying on staff to clean first andthen disinfect is more reflective of real world conditions.

Martin Favero, PhD, director of scientific and clinicalaffairs at Advanced Sterilization Products in Irvine, Calif., and formerly withthe CDC, agrees with Fauerbach, taking it one step farther: Intermediate andlow-level disinfectants are targeted to environmental surfaces and / or they areused for housekeeping purposes. He adds, When the new CDC guidelines arepublished, there will be a section where they talk about whether you need anantimicrobial agent in a detergent when you clean a hospital.

Sanja Valentic, senior product manager for environmentaldecontamination and instrument transport at Mentor, Ohio-based STERISCorporation says, Were moving toward new products with new infectioncontrol needs, new pathogens, and using new methods to control and to test them.Microgen and STERIS are both in line with changes that are happening globally.Were looking at prolonged efficacy. Were looking at new pathogens. Werelooking at new testing techniques. In the marketplace, were keeping ahead ofwhere it stands. Our background is in acute care, especially in hospitals wherequality infection control is imperative. Were not a janitorial supply company. We have a sciencebase to all of our testing and all of our practices.

Taking It to the International Level

Many countries in Asia, Africa, and even Europe have been hitwith extremely virulent disease outbreaks, both human and animal. Does theimportance of how a disinfectant is tested change when disinfectant products areused in less than hygienic areas of the world?

Cheyne Gable of Marietta, Ga.-based ATCO Internationalbelieves that testing is important. The importance of testing a disinfectantunder higher soil loads and in hard water conditions becomes even more importantunder such circumstances, he claims. Disinfectant manufacturers have historically testedproducts in fairly benign laboratory conditions. The problem is that these conditions do not always adequatelyrepresent the conditions in which the products may be used, especially in areasof the world that have different hygienic standards. We have seen the effectsthat a regional outbreak, such as SARS, can have on the rest of the world insuch a short period of time. The efficacy of disinfectants is no longer aregional but rather a global matter.

Reid does not believe this is an important issue. He says, Inmy view, attention to process and protocols are more important than individualdisinfectant efficacies. The global community and movement of people, animalsand produce require attention to detail and the identification of control pointsin these systems. Risk-based prioritization of surveillance and the applicationof Hazard Analysis and Critical Control Point (HACCP)- based principles will beinstrumental in this control and risk mitigation. Disinfection has a key role toplay at certain control points.

Favero offers another important point, stating, I believethat cleaning followed by a disinfectant, even one that may be a littlecompromised would end up being of the same importance in the U.S. or in adeveloping country.

Fauerbach adds, In many third-world countries simple meansof cleaning are used such as soap and water and disinfection may be done withchlorine bleach, which is not very expensive.

Javadian believes that it is up to the companies thatmanufacture good disinfectants to make sure their products get to the areas mostin need, and is an advocate of high OS testing. I travel a lot in relation tomy job and what I see, particularly in places like South Africa and Asia, theyare really lacking in even basic hygiene. That is why I encourage all thesecompanies to get their products one way or another to those countries. A 95percent soil load testing of these quat agents is important. I have seen the long list of efficacy against viruses, fungiand bacteria. On the global level, in all developing countries they need thesetypes of agents (disinfectants) to prevent the spread of disease as much aspossible. This goes back to even the hospital settings which are very differentfrom the sophisticated hospitals of the more developed countries.

Germs hide in soil where they reproduce. Organic soil is aprotected shell of food for them. The authorities are unanimous on one thing:Get rid of food waste. Upgrade hygiene standards; clean first, then use adisinfectant, regardless of how effective a disinfectant is in the presence ofsoil. Most any disinfectant is better than no disinfectant; one rated for use inhigh soil load may have added benefits.


In the U.S., the EPA has been given the authority by Congressto set the standards for all disinfectant efficacy claims. This body hasapproved the claims of disinfectants tested for pathogen efficacy under muchhigher than required OS load and in hard water. The user only has to read anyproduct label to see whether it has been tested for efficacy under enhancedconditions.

The cleaning step is an important one to remove bioburden andmake any disinfectant more productive, however, cleaning may not be performedadequately.

Matthew Arduino, of the CDC, concludes, The labels ofEPA-registered disinfectants usually specify that the product is to be used on apre-cleaned surface. In our opinion, if people followed label instructionsconsistently, the need to verify that the products worked in the presence ofhigh organic loads would be reduced. People, however, often do not clean surfaces as they should,so the potency testing in the presence of high organic loads continues.

Gail Stout-Flower is the former editor in chief of InfectionControl Today and the current editor in chief of AdvancedPackaging and SMT magazines. She may be reached at (603) 261-9090 or a complete list of references, contact the author.