Q&A With Dr. Sarah Simmons on Lab vs Real World Testing

This interview with Dr. Sarah Simmons explores her mission to help improve the way surface disinfection technologies are validated, so that testing standards for everyone are the same (comparable), and that those standards mimic conditions in real hospital environments. Dr. Simmons believes improving these standards will lead us to faster improvements in adopting effective disinfection programs and ultimately avoid unnecessary infections and deaths.


What is your role at Xenex?

As the Science Director, I oversee all Xenex research and help hospitals with their strategic use of Xenex Robots.

I’m an epidemiologist and biostatistician, so a lot of my day is about helping our customer hospitals analyze their own complex data sets. We help them quantify the positive impacts Xenex disinfection is having on their Hospital Acquired Infection (HAI) rates, as well as on their bottom lines. I also hold a certification in Infection Control (CIC), and consult with infection prevention teams at hospitals that are considering our disinfection program, to help them project the impacts they could see.


What kind of labs does Xenex use to confirm the disinfection effectiveness of their Robots?

We use several types of labs. While we have our own research lab, our 3rd party microbiology labs also confirm efficacy in a lab setting. We work with Texas Biomedical Research Institute on Ebola and Anthrax last year, so that was really exciting, since we are the only disinfection company to test against those actual pathogens in a Biosafety Level 4 lab. I should add, those tests came out beautifully and showed that pulsed xenon UV completely kills Anthrax spores in 15 minutes and Ebola in 1 minute!

We’ve also worked with governmental labs and international labs confirming Xenex efficacy against many highly resistant pathogens and rarer ones like MERS-CoV, which is a problem in the Middle East.

You asked about effectiveness and actually, “efficacy” refers to a lab setting while “effectiveness” is how well you perform in the clinical (or real-world) setting. Hospitals have demonstrated Xenex effectiveness in 8 peer reviewed studies on HAI rate reductions.


Studies are often performed in a hospital room setting on inoculated surfaces, such as Formica plates, as a substitute for actual contamination in the hospital environment. Is this the best way to evaluate the effectiveness of these technologies?

No, it certainly isn’t. There have been many such studies, but several including the most recent of those calls into question the standards for lab evaluations. Something as simple as placing the slide or Formica plate parallel to the bulb, or horizontal (on a table or bed) can drastically affect results. Hospital surfaces are not all vertical, so we can not rely on those results to translate in the real world. That’s why it’s so important to look at peer reviewed, published outcome studies that show impacts on patient HAI rates in hospitals.


How are dosimeters important to UV disinfection technologies?

Dosimeters are meant to measure the output of a bulb at its source. Some devices claim to measure reflected UVC ‘dosage’ that bounces off of surfaces in the patient rooms.

However, UVC light is absorbed by most surfaces, and therefore you can’t rely on UVC light to “bounce back” to a dosimeter off of a wall or a plastic bed rail. And that’s exactly why Xenex recommends multiple positions in the room to ensure all surfaces are exposed to the germicidal light.

So on Xenex Robots, the dosimeter ensures that the output of the bulb is strong enough to kill C. difficile spores (one of the hardest  pathogens to kill). If we’re killing C. difficile, we know we’ve also eliminated viruses and vegetative bacteria.


How could we improve the way we validate surface disinfection technologies?

There should be standards that everyone follows, in the same way that we have standards for how clinical drug trials have to be designed. It’s too confusing for hospitals trying to decide what is proven, what is effective, and what will achieve a measurable outcome for them. If all the testing standards were the same, then the results would be easy to compare.

For example, many infection preventionists focus on the log reductions that a disinfectant can provide. And some studies on Formica plates are impressive. But the studies conducted on real surfaces, contaminated with real bioburden from patients, show that you just don’t see 6 logs (essentially millions) of bacteria on surfaces in hospitals. So we shouldn’t talk about killing things that aren’t there! We should talk about our efficacy against what is really there, and I think the focus should be on C. difficile.

C. difficile is the biggest HAI problem we have in the U.S., and it’s difficult to clean and kill. If C. difficile was the standard organism against which all disinfectants had to be validated, I think there could be a more honest discussion about how they perform comparatively. Xenex is the only device that has a four minute disinfection treatment cycle for C. difficile, but more importantly Xenex is the only UV disinfection device that has multiple peer reviewed published studies that confirmed reduced rates of  C. diff, MRSA, VRE and SSIs in real hospitals — repeatedly. Patients are waiting; I think we should all be in a rush to reduce HAIs.

Credit xenexadmin