This recent study from the Donskey group could provide hospital cleaning staff with a powerful visual cue to help assure adequate disinfectant coverage. The addition of a chemical widget to bleach solution gives it a bright blue hue when applied to surfaces, so allowing a cleaner to track their progress visually!
The widget is called ‘Highlight’, and interacts with chlorine to turn a chlorine solution bright blue for 5 hours in solution, or for about 5 minutes when dried on a surface. Lab testing performed as part of the study demonstrated that adding the marker powder to 0.65% sodium hypochlorite did not reduce its efficacy achieving a 6-log reduction in C. difficile spores. Then, the team performed an experiment in which 9 healthcare personnel were asked to judge visually whether a surface had been sprayed with sodium hypochlorite solution, which was randomised to either containing the marker or not. Perhaps unsurprisingly (see the stark figure below!) almost all staff were able to spot when the marked solution had been applied (in fact, it was amazing that this was not always the case!).
Figure: A bed rail with application of chlorine versus marked chlorine.
I really like this study. We have been taking about additives to provide visual cues for those performing cleaning and disinfection at the coal-face for years, so it’s great to see a promising product coming through. This short study raises some interesting questions and possibilities:
- Could this help to provide some assurance on achieving an appropriate contact time in addition to adequate distribution of the disinfectant?
- Can this or other related products be used for other disinfectants?
- Do we want the colour to fade after 5 minutes, or do we want it to start green to assure initial distribution and turn red after 24 hours if the surface isn’t cleaned again?
- How would patients feel about hospital surfaces turning bright blue (albeit transiently)?
- How do staff feel about having their ‘performance’ highlighted so obviously?
- The study mentioned that the marker left a blue residue on some parts of some surfaces that was wiped off easily. I wonder how this would play with damaged or fragile surfaces?
Visualising microbes themselves probably isn’t going to happen any time soon. But this study shows we can at least have some visual cues to help us improve hospital cleaning and disinfection. I hope that this short research letter will prompt some larger studies to explore this potentially very helpful development in more detail.