Abstract
Floors are an underappreciated fomite or source of pathogens. These pathogens can transfer to our hands, and from there, further spread to other surfaces including our mucosal surfaces, which can make us sick. Unfortunately, regular cleaning of floors (typically through mopping) is not sufficient, as the number of bacteria, fungi, and viruses can easily be replenished through the introduction of outdoor sources on shoes. Eliminating these pathogens at multiple entry and exit points can greatly reduce the spread from different areas, and are further enhanced by employing combination disinfection, which is the use of two complementary technologies to eliminate harmful microorganisms.
Main Article
Hospital Acquired Infections
The floor in public buildings is unique in that it is remarkably similar to the outdoor environment. Through shoes, cars, carts, and all other manner of ground transport, dirt and debris from the outdoor environment are carried indoors (Weinstein and Hota, 2004). These floors are cleaned regularly, but given the focus on hand hygiene and other mucosal surfaces, little thought has been given to its ability of the floor to transmit diseases. The presence of bacteria has even been identified on operating room floors, where sterility is extremely important. This has been an ongoing for decades, as this was first reported in the 1980’s (Suzuki et al, 1984).
Floors are Unique
It should be noted that the presence of bacteria alone is not a cause for concern. We are surrounded by them, and for the most part, unaffected by their presence. Problems arise when bacteria infect those who are immunocompromised, such as the young, elderly, and infirm (Rutala and Weber, 2001). Recently, a study analyzing hospital floors found that the floors acted as a fomite and can transfer pathogens to people. This was hypothesized as the floor comes into regular contact with surfaces that are subsequently in contact with hands (Koganti et al, 2016). In fact, the authors claimed that the floors were an ‘underappreciated reservoir for pathogen transmission.’ In a follow up study of five hospitals, the researchers found that additional surfaces that are not typically on the floor were likely to be in contact with the floor, such as call buttons and blood pressure cuffs (Deshpande et al, 2017). Despite numerous policies describing how best to store and isolate this equipment, compliance is still a major issue. These surfaces are constantly touched by patients and a multi-faceted approach is required to help reduce the incidence of floor-borne hospital acquired infections (HAIs).
the floor might require even more extensive cleaning than surfaces
In fact, the floor might require even more extensive cleaning than surfaces that come into contact with mucosal surfaces. Despite innovative technologies with varying efficacies in pathogen reduction in floor cleaners, the floor is unique in that the bacterial load is constantly being replenished through the influx of contaminated shoes that enter the building (Kramer, Schwebke and Gunter, 2006). Floor cleaning is not fruitless, as it removes soiling that can help to protect some pathogen populations (Prout, 2009).
Economic Impact
The floors are an underappreciate source for pathogens and this can have a real financial impact on our healthcare systems. It has recently estimated that HAIs cost the healthcare system 9.8 billion dollars (USD) annually in additional costs (Zimlichman, 2013). This meta-analysis found that at least half of these infections were preventable. The costs of HAIs due to floor contamination have not yet been calculated, as direct contamination rates are difficult to isolate. Regardless, reducing floor-related HAIs has the potential to save millions annually.
Mitigating Spread
As previously stated, floor contamination is unique, and thus needs specialized care. When entering contaminated rooms, staff are usually instructed to don or change gowns, as well as gloves, masks, and caps. This is helpful for the protection of the wearer from what is in the environment and can help prevent the spread of harmful pathogens most of the time. What many users often forget is that until we remove the personal protective equipment we are wearing, the pathogens are still on us, and can continue to spread. The floor is especially harmful, as every step a person takes can transfer more pathogens. Constant donning and removal of booties at entrances and exits can mitigate this transfer, but this is burdensome, and can further contaminate hands during this process (Humphries et al, 1991).
In practice, floors are cleaned regularly with a disinfecting solution and soil removal. This has the added benefit of removing compounds that can reduce the efficacy of cleaners. Due to limited resources (typically cleaning staff), the intervals between cleaning can be quite high, allowing for the accumulation of viruses and bacteria (Andersen et al, 2009, Otter et al, 2015).
Recently, ultraviolet (UV) irradiation has been embraced as an additional technology that can reduce the spread of pathogens. By having users irradiate their shoes every time they enter or exit a room, we remove a significant dissemination step for pathogens. UV, and especially ultraviolet C (UVC), has been shown to have incredibly efficacy in the reduction of bioburden on numerous hospital surfaces, including whole room disinfection (Boyce, 2016, Rutala, Gergen & Weber, 2010). Given its mechanism of action, excessive exposure to UV is not recommend, and is usually employed on empty rooms or within enclosed spaces. Fortunately, its exposure can be easily confined, and unlike chemical disinfectants, has no negative impacts after the radiation is applied. Thus, it makes sense to incorporate this effective technology into higher volume spaces when possible.
Combination Disinfection
There are countless tools available for the disinfection of public spaces, but these are mostly based on a handful of technologies that have been shown to be effective. When two complementary technologies are used in combination, any pathogens that might survive one compound, is not likely to be resistant against both. This is already employed in agriculture to curb the spread of salmonella, where UV irradiation is combined with hydrogen peroxide for the disinfection of eggshells (Wells et al, 2010). A similar finding was found for the combination of UV and ozone disinfection for cut vegetables (Selma et al, 2008).
The use of any two disinfecting agents is not sufficient. It is important to select two complementary approaches to provide a greater overall bioburden reduction. For example, for the treatment of aggressive infections, different classes of antibiotics can be used in conjunction, but prescription of different medications within the same drug class are largely ineffective. This principle of combination disinfection has the potential to extend the shelf life and effectiveness of many current cleaning technologies.
This has been employed by companies like PathO3gen Solutions in their development a footwear sanitizing station (FSS) that is installed in public spaces to disinfect users’ shoes with both UVC and ozone as a two-pronged approach to eliminating harmful pathogens on the floor. Preliminary studies of the FSS have shown a greater than 99.6% reduction in methicillin-resistant Staphylococcus aureus (MRSA) populations.
Conclusion
The spread of harmful bacteria and viruses through the floor is an under-appreciated threat to hospital staff and patients. Its constant exposure to the outdoor environment through foot traffic replenishes any attempts to curb the bioburden through regular cleaning. Technologies such as UV are effective in reducing pathogen populations, but the inability to use them in occupied areas reduces their efficacy for public spaces. The use of combination disinfection brings together the benefits of complementary technologies to make up for any downfalls associated with either product to create a more effective disinfection tool.
References
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