It is well established in infection prevention practice that surfaces in hospital rooms are continually contaminated by infectious pathogens. The sources of these dangerous pathogens range from people who enter the room with contaminated hands and compromised clothing, from contaminated instruments and items that are brought in and out of the room like personal and enterprise issued mobile devices, and from the patient themselves. In addition, the air entering the room is not sterile and deposits pathogen containing fomites which settle onto all the surfaces adding to the degree of bio burden compromise.
It is also well established that the accumulated pathogens residing on high touch surfaces are then transferred onto bare or gloved hands and clothing of nurses, doctors, visitors, and environmental workers when touched, which in turn puts patients at great risk since they or their immediate surroundings are consequently contaminated by touch transfer mechanisms. Hence, even perfect attention to between patient visit hand sanitation by healthcare workers (HCWs); 100% compliance, and effective sanitization of hands to – 4 log10 inactivation, (99.99%); which is not currently achieved), will leave the hands contaminated while performing tasks within the room. This situation is judged to be unavoidable.
Accordingly, the ultimate solution espoused by WHO is hand sanitation immediately prior to patient contact; the Five Special Moments (‘FSM’), so that patients or the patient’s surroundings are not contaminated as a result of attention or care from a healthcare worker, attendant, or a visitor. Currently, the use of alcohol rubs just prior to contact is recommended by WHO for hand sanitation despite the fact that during a shift 100 or more alcohol rub hand sanitations, each taking at least 30 seconds, almost one hour dedicated to hand sanitation per shift, would be required. Moreover alcohol rub is not free of hand irritation and is totally ineffective on spores such as C. diff and some viruses. Hand washing is usually less effective, takes more time and is generally more irritating. There is no currently available product that can meet the WHO FSM requirement so it remains an objective, but not yet a reality.
As a response to problematic hand hygiene, a number of companies are now offering UV-C-based, room disinfection devices which have as their purpose to supplement terminal cleaning. They nominally sanitize room surfaces in as little as 15 minutes, and by lowering bio burden levels, help to minimize additional contamination of hands and clothing when the surfaces are contacted later. This sanitation process must be carried out in a vacant room due to the dangers UV-C poses to unprotected eyes, so it is generally performed only after patient discharge and cleaning by environmental workers.
To understand the efficacy of this approach, it is important to recognize that to inactivate pathogens, especially hardy C. difficile endospores, to the nominal – 4 log10 or 99.99% sanitation level in 15 minutes, typically requires a direct, continuous, line of sight UV-C dose for the entire 900 second period on the entire surface area. Keeping in mind that UV-C intensity of a source falls off with dramatically with distance from that source. This approach could be effective in sanitizing most of a room’s surfaces from normal incidence rays falling directly on these surfaces. This would be the case for walls, which are actually not touch surfaces in most cases.
However, most touch surfaces in the room are generally not perpendicular to the UV-C rays coming from the source. A desk or table or bed surface is in fact almost certainly at a large oblique angle to the UV-C rays from a single source. So for example the effectiveness of radiation at 45 degrees to a surface would only achieve approximately 70%, of an ideal dose which achieves an expected 99.9% level when delivered directly perpendicular to a surface. For light traveling parallel to contaminated surfaces there can theoretically be virtually no inactivation.
While the walls of the room may be fully sanitized, the disinfection level of important high touch surfaces, like telemedicine devices, may be in question. UV-C room sanitizer systems for this reason alone may not be achieving expected 99.9% efficacy for most pathogens in the room. Of course, there is no easy fix to overcome the limitation of optics. Some have suggested multiple emitters, to flood the room with UVC from different points, but this creates its own problems associated with additional down time and usage costs.
There is also the challenge of how to deal with shadowed areas not reached by the UV-C light. If UV-C disinfection purpose is to help rectify inadequate terminal cleaning, attention must be paid to the fact that most surfaces are still dirty at the time of terminal cleaning. Soiled surfaces are a serious problem since most biofilm, settled dust, and human excrement or spatum is opaque to ultraviolet rays and will shield pathogens within or below its surface. Disinfection quality of the target surfaces will be impeded if they are not fully cleaned prior to exposure to UV-C. Depending on the level of contamination, pathogens can clump together and become only partially transparent to UV-C. Some of the pathogens within the clump may be shielded from the UV-C; reducing the received dose and the overall degree of inactivation achieved.
There are many factors that quickly build up the contamination level of a patient room; non sanitized clothing and compromised hands of HCWs, germ carrying visitors, pathogen laden mobile IT devices, compromised terminal cleaning processes can put the patient at risk.
There is no silver bullet to the global HAI problem. But UV-C, in combination with diligent terminal cleaning processes, and behind important hand-washing initiatives need to be part of an entire eco-system that addresses not only clinician hands, the patient’s room, but also tablets, phones, and other roaming, transient, high-touch surfaces. These solutions need to work together for an all encompassing approach to the problem and work in concert to provide a safer patient and worker environment.