Few doubt the value of regular surface disinfection in hospitals, schools, and other institutions. However, there is a healthy debate taking place within the environmental services and infection control communities, attempting to address a fundamental conundrum – which surfaces to disinfect, how and how often?
Two questions are central to the first part of the debate. “On which surfaces are pathogens likely to reside?” and “What is the risk associated with different surface types?” While a great deal of scientific information has been generated in this area, and sorting through the science can be challenging, common sense applies.
Typically germs live in moist places and in places frequently touched. Also virtually all studies agree that microorganisms can persist on surfaces for long periods, although on dry and less-frequently touched surfaces, germs are in various stages of dying off (Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcci (VRE), etc. survive much longer on a dry surface than Gram-negative bacteria such as E. coli, Salmonella, etc. Fungi also survive for long periods on dry surfaces, as do bacterial endospores such as Clostridium difficile, etc.)
Since germs eventually die on dry surfaces, and most environmental surfaces are dry, it is reasonable to conclude that wet surfaces and dry surfaces with the high germ deposition rates (a.k.a. high-touch surfaces) will be the most contaminated within any environment.
The Question of Risk
Of course, while microorganisms are ubiquitous on environmental surfaces, not every microorganism has the ability to cause disease. Thus, there is a big difference, from a risk perspective, between a surface contaminated with germs and a surface contaminated with pathogens – microorganisms capable of causing disease.
Also, an environmental surface must be contaminated to contribute to disease transmission, and there must be an opportunity for that contaminant to make the jump from the surface to a person – that is, for a surface to pose a risk, there must be a potential for exposure to the pathogen.
Toilets bowls are highly contaminated, but rarely touched, so they are not high-exposure, high-risk surfaces. Hospital bedrails, door handles, tabletops, IV poles, bedding and other surfaces are a different story; while they may not harbor the same high concentration of pathogens found on a toilet bowl, people do touch such surfaces on a regular basis. Thus, exposure to pathogens on high-touch surfaces is much greater, and therefore the surfaces pose a greater risk to health.
High-touch surfaces have also been identified in recent years as hotspots of surface-mediated pathogen transmission, especially in hospitals.
Thus, since touch points are the intersection where germs reside, stay alive and are easily transmitted, they should be our primary focus; although damp places and germ reservoirs such as sink basins, adjacent countertops, and restroom toilets and floors should also be regularly included in an overall preventive program.
Increasing the Frequency of High-Touch Surface Disinfection
Obviously, the fewer pathogens on a high-touch surface the better. But it is impractical to disinfect a surface every time it is touched. In “real life” most high-touch surfaces are disinfected once a day, at best. Disease transmission by high-touch surfaces could be better controlled by increasing the frequency with which these surfaces are disinfected. However, increasing the frequency of disinfection naturally amplifies the negative attributes of the any disinfection technology (e.g., toxicity, corrosiveness, etc).
