The stainless steel surface is so clean you can see your reflection in it. But an invisible danger remains: infectious microbes lying in wait to contaminate the next item they touch and transmit dangerous infections to the next patient you treat.
Yes, “visually clean” high-touch surfaces can harbor contamination. Look around at your high-touch surfaces: keyboards, touchscreens, light switches, phone, bed rails, the over-bed table, call buttons and patient care equipment. Even the OR floor. If they appear to be clean, they might not be.
“These surfaces are of high concern because surfaces that are in closer proximity to an infected patient have the highest probability of becoming contaminated by the patient shedding virus or bacteria,” says Christine Greene, MPH, PhD, principal research investigator in contamination control at NSF International.
A 2011 study found that of the 80% of high-touch surfaces that passed visual assessment, only 19% were found to be microbiologically clean (Ferreira et al., 2011). Another study found that of the 82% percent of the surfaces that passed visual inspection, only 30% were found to be microbiologically clean (Griffith et al., 2000). Common organisms found on theses surfaces include methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), Acinetobacter baumannii and Clostridium difficile, to name just a few.
More bad news: Current measuring tools for verifying cleaning may be coming up short. One of the most commonly used tools to measure and monitor contamination removal in the healthcare setting is adenosine triphosphate (ATP) testing. ATP is the universal unit of energy in all living cells. But many in the industry are questioning the usefulness of ATP residual testing in overcoming the actual challenges of surface cleaning and disinfection.
“ATP does not measure chemical efficacy,” says Maurits Hughes, director of logistics and support services at the University of Michigan Health System. “It measures cleaning efficacy. This means if organic material is measured by ATP, it cannot distinguish whether it is alive or dead.” ATP’s inability to distinguish between organic materials could undermine the overall success of your infection prevention program.
“ATP bioluminescence detection works by capitalizing on the ability to measure light — in relative light units or RLUs — as a result of a chemical reaction between ATP and luciferin,” says Dr. Greene.
“Since ATP is found in all biological cells — such as skin, food, microbes and other debris — the RLUs resulting from a normal ATP test in a perioperative setting are non-specific and reflect the ATP from all sources.”
Ironically, even residues from some cleaning products can react with the ATP test, resulting in inflated or under-inflated results. “Bottom line: You should not rely on this test as an indicator of proper disinfection, even if it is a good tool to confirm that cleaning has been performed,” says Dr. Greene.
Related challenges with ATP are the lack of standard benchmarks to classify surfaces as clean by ATP assays, and the variation in sensitivity and specificity between different luminometers and assay systems. “Some ATP systems classify surfaces with < 250 RLUs as clean, while other systems classify surfaces with < 100 RLUs as clean,” says Dr. Greene, “leaving end users without clear definitions of clean, from facility to facility, and product to product.”
Simply identifying the shortfalls of ATP testing, however, will not bring us any closer to safer patients and cleaner surfaces. Perioperative teams and infection preventionists need a way to detect true contamination of surfaces. So what are your options? Mr. Hughes believes the future of microbial monitoring lies in culturing surfaces to provide better results of the efficacy of disinfection and sanitizing.
This type of microbiological culture sampling is best performed with a moistened swab with enrichment broth or agar (rodac) contact plates, says Dr. Greene. “In either case, the sample is sent to a lab and analyzed for the total number of microbial colonies. In the most basic way, samples can be analyzed for total aerobic plate count (ACC). For the ACC test, a benchmark of <2.5cfu/cm2 of microbiological growth is used as an indicator of cleanliness.”
The good news is that it is becoming increasingly affordable to look for specific microbes of interest as well, such as VRE, MRSA and C. diff. Although microbial swabbing can generally take up to 48 hours to get a result, Dr. Greene believes it is far superior for assessing microbiological contamination and worth using for routine monitoring and validation of cleaning processes.
“Microbiological assessment of cleanliness,” she argues, “is the only way to know if you’ve properly cleaned for the removal of contamination. This is critical in the healthcare environment which attends to those already unwell — and potentially most vulnerable to infection.”
While it makes sense to focus on the obvious dangers of high-touch surfaces, there are other threats that also require your attention. The impact of floor contamination is one of those topics that can literally be overlooked in terms of importance for providing a safe space for perioperative patients. “Items dropped on floors can easily transmit microbes from the floor to the person picking them up,” says Mr. Hughes, “and patients can transfer microbes from the floor into the bed by simply walking on the floors.”
Surprisingly, hospital floors are rarely found on the list of “high-touch” surfaces, notes Dr. Greene, yet floors are one of the most repeatedly contaminated surfaces in the room.
“As we walk from outside to inside, we bring any bacteria from the outside with us. Since floors are almost never disinfected, contamination can be moved easily via the bottom of our shoes,” she says. “Even the seams and cracks in a floor can harbor communities of pathogens in the form of biofilms.”
Other areas and items that may be classified as low-touch can still become a source of cross-contamination. Microbes do not discern between low- and high-touch surfaces. As Dr. Greene explains, “Left undisturbed, many microbes can go dormant and survive just fine in dust. Once the environment becomes habitable again with the addition of nutrients, those microbes can become viable again.”
Dr. Greene cites a 2015 study by Albert Barberán et al., that characterized the microbial communities of household dust and found that there were thousands of species present. The study (osmag.net/SNz3wP) also found that the composition of the bacterial populations found in the indoor dust was a function of the occupants that resided there.
A robust infection prevention program, argues Mr. Hughes, would support the use of a disinfectant in a facility’s floor cleaning protocol. “After this, the next step would be to culture the floors in perioperative areas to measure cleaning efficacy and bolster the overall process,” in addition to highlighting the importance of dust removal in support of the entire cleaning program.
One of the remaining challenges for those on the frontlines of the fight against SSIs and HAIs, explains Dr. Greene, “is the lack of sufficient recommendations and guidelines on the proper cleaning and disinfecting of flooring.” Workgroups within organizations such as the Healthcare Infection Transmission Systems Consortium (HITS) are attempting to tackle this very issue, but consensus documents have yet to be published.
Microbial sampling and culturing is currently the only way to know if cleaning and disinfection processes are adequately removing contamination from high-touch surfaces in the OR, or other critical areas such as flooring. “Microbial sampling can provide confirmation that the cleaning processes — especially in critical areas such as the OR and ICU — is actually working,” says Dr. Greene, “or it signals that you need to step up your surface disinfection game.” OSM