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Antibacterial Cleaning Agents-Being Clear about the Issues
Debate over Impact of Antibacterial Cleaning Agents Rejoined
In the current conflict over the benefits or otherwise of using antimicrobial cleaning products in the home (ASM News, March 2001, p. 130), one of the key factors perpetuating the conflict is the fact that the protagonists are not comparing like with like. On one hand, arguments against the use of these products focus mainly around "routine cleaning" and the use of cleaning and other products supplemented with antibacterial agents, while arguments for their use relate to the process of "active intervention to prevent cross-contamination and cross-infection."
Daily or weekly "routine"cleaning of the home to remove dirt, etc., is assumed to have some impact in reducing infectious disease, the major benefit being that regular cleaning plays a key role in removing the "breeding grounds"for germs. This being the case, adding antimicrobial agents to such products offers no real benefit. In hospitals and other settings, where hygiene plays a key role, the idea of producing a "germ-free" environment has long been abandoned in favour of a Hazard Analysis Critical Control Point (HACCP)-based approach in which high-risk sites, surfaces, and activities are identified and hygiene practice focused on reducing these risks. By contrast, the concept that "getting rid of all household germs is the means to protect the family from illness" is still strong in the mind of the public.
In the past few years, research studies focusing on the home have not only given us a clearer understanding of the importance of the home setting in transmission of infection and how infectious diseases are spread in this environment, but indicate that a significant proportion of these infections are preventable through improved hygiene. These studies show that sources of pathogens are frequently present in the home (in contaminated food and associated with infected people and pets) and that significant numbers of these pathogens are readily spread around the home environment during normal daily activities, either directly or indirectly via hands and other surface or via the air. Such studies suggest that a risk-based or "targeted" approach to home hygiene could have significant impact.
Within a targeted hygiene approach, safe and effective hygiene procedures for minimizing risks of transmission can then be identified. Detergent-based cleaning, provided it is carried out with thorough rinsing of surfaces, will give adequate risk reduction, but evidence from home-based studies shows that use of a product with appropriate antimicrobial properties in addition to cleaning gives an additional margin of safety by increasing the probability of achieving a satisfactory result. The evidence thus suggests that, within a targeted approach to home hygiene, disinfection is advisable in certain situations where hygiene failure carries a risk of serious consequences. This includes, for example, use of disinfectants for food contact surfaces which are used during the handling of raw foods, most particularly large surfaces and surfaces such as handles which cannot be adequately rinsed, or surfaces such as chopping boards which are inevitably damaged during use and are difficult to "clean" effectively.
To benefit from using an antimicrobial product it is necessary, of course, to ensure that the product has activity appropriate to its intended use within the given situation. Antimicrobial agents currently used in hospitals and other settings have widely differing properties and, as such, it is impossible to generalize about their benefit-risk profile since this will vary from one product to another and from one situation of use to another. A factor which undoubtedly also perpetuates the confusion is the lack of clarity about the meaning of the term "antibacterial." Is an antibacterial product different from a disinfectant, or is it a generic term which encompasses all products with an antibacterial action? In many cases it appears that the former is intended by the writer, but the latter is assumed by the reader. Stewart Levy in an early article raising concerns about antibacterial products stated that "simple, quickly evaporating chemicals such as chlorine bleach, alcohol, ammonia, and hydrogen peroxide can be applied beneficially."
Growing interest about home hygiene has led an international group of experts to form the International Scientific Forum on Home Hygiene (IFH). This organization aims to raise awareness of the role of home hygiene in preventing infectious disease and promote understanding of practice, based on evaluation of the scientific principles. As part of this work the IFH has produced guidelines for home hygiene. The key feature of these guidelines is that they are based on the concept of risk assessment and risk prevention.
In assessing the value of biocidal products, it is vital that the benefits are balanced against potential risks, which include concerns about antibiotic resistance and possible effects on the immune system. The concept of targeted hygiene also provides a means to address these concerns in that it provides the most effective means to fight infectious disease while disturbing the balance of our human and natural environment as little as possible. Although the risk-benefit debate cannot be fully resolved in view of our incomplete picture of the scientific facts, perhaps it is time that we stop focusing so entirely on the idea that effective home hygiene means either antibacterial or nonantibacterial products and become more effective in communicating what good home hygiene really means.
Sally F. Bloomfield
Unilever Research
Wirral, United KingdomPeter Gilbert
University of Manchester
Manchester, United KingdomThe article "Debate over Impact of Antibacterial Cleaning Agents Rejoined" (ASM News, March 2001, p. 130) revisits a serious concern of many microbiologists from the industrial sector. The concern—the seemingly obsessive need for disinfection in society. Just about every class of product has a small percentage of "antibacterial" or "antimicrobial" products. This seems to have started with the antibacterial soaps originally intended for use by physicians before entering an operating room. Then, these products became available to the general public and the floodgates opened. Now there are soaps, gels, lotions, kitchen utensils, and even TOYS! All with antimicrobials. A quick survey of the products leads to the realization that the most common active ingredient is triclosan.
The choice of this ingredient is somewhat curious however considering (i) the relative ineffectiveness of this active ingredient against Pseudomonas spp., (ii) the increasing recognition of pseudomonads and related genera (e.g., Burkholderia, Aeromonas, and Stenotrophomonas) as opportunistic human pathogens, (iii) the efficiency of horizontal gene transfer between members of these genera, and (iv) the time-kill curve kinetics of triclosan with respect to this group (or any organism) are usually dependant on "bioavailability" (with respect to the target organism) of the active. This becomes especially important with "impregnated plastics (i.e., toys and kitchen utensils).
However, even with all of these factors, and now a scientifically controlled study showing what many believe is an impressive series of data, skeptics still say this "all-out war" and "take-no-prisoners" attitude towards bacteria is justified and even beneficial. I wonder just what it will take to convince these individuals. I do agree with Philip Tierno on many of his arguments. No "experimental control" result is ever absolutely correlated to the "real world." Also, his competition argument must be accepted since "pure" cultures are "never" found naturally. By the same token, when companies prepare to market these products they perform either MIC tests, time-kill studies, MBC tests, or any combination of these all with fresh "pure" cultures.
Pseudomonas spp. are extraordinarily resistant bacteria with resistance mechanisms which are at best poorly understood. They are also among the most dangerous bacterial infective agents for this reason. Even more importantly, this genus is ubiquitous in nature—especially in water. This makes it even more important to account for potential resistance in these organisms.
It is interesting that the position of the U.S. Food and Drug Administration (FDA) on antimicrobials (in particular preservatives) is one of precautionary use. According to the FDA, manufacturers are not expected to use preservatives to "fix" current good manufacturing practices (GMPs) but as a protective measure for consumers during use of multidose products. Then these companies have taken complete advantage of the media blitz from the few isolated cases of bacterial infection and created a frenzy of activity around these cases. This further fostered the "scares" of potential infection.
In all honesty, if I were taking home a dear aunt who was found to have emphysema or any other major lung disorder, skin disorder, or other difficulty, I surely would NOT be buying "antibacterial" soaps, lotions, or kitchen tools. The risk is too great to take with someone who I care about. The misconceptions by my colleagues on the medical side of the fence seems to be caused by an arbitrary abyss between the medical and the industrial sectors. This is a real-world case where the industrial sector seems to understand a little more about the medical problems associated with product use than the medical microbiologists do. Maybe it is time for both groups to close that abyss and get down to the more important issue—let's keep everyone safe with COMPLETE information instead of the misconceptions.
Victor Mencarelli
22 Healthcote Road
Lindenhurst, N.Y.
QCSientist@aol.com
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