ICT spoke with David J. Weber, MD, MPH, of the Departments of Medicine and Pediatrics at the University of North Carolina, Chapel Hill, to gain his perspectives on a number of important issues relating to the prevention of healthcare-associated infections (HAIs).
Q: Instrument- and device-related outbreaks are still making news, so what's most important to bear in mind relating to the proper cleaning, disinfection and sterilization of surgical instruments and medical devices?
A: One key concept for proper disinfection and sterilization is following the Spaulding classification which bases the type of disinfection and sterilization on the use of the item. Instruments that enter sterile body tissues must be sterilized; instruments and devices that touch mucous membranes and non-intact skin should at least be high-level disinfected; devices that touch intact skin should be low-level disinfected. The other key concept is that cleaning must always precede disinfection and sterilization. You can make almost any disinfection process fail if you have inadequate cleaning. The method of choice for sterilization is always steam sterilization because it has the widest margin of safety. My colleague and sterilization expert Dr. William Rutala would say too there has never been a failure of steam sterilization as long as the proper temperature is reached.
Q: Why is it important to consider the role of the environment in the transmission of pathogenic organisms?
A: In the March 2011 issue of Infection Control and Hospital Epidemiology is a paper by Dr. Shaughnessy that demonstrates if you are admitted to a patient room where the previous patient had C. difficile you have a higher risk of acquiring that pathogen. This has also been demonstrated in the past for MRSA and VRE. So we have three pathogens and multiple studies all showing that if you are put into a hospital room with a prior patient who had that disease, you could become infected. Now, the problem is not that the cleaning agents -- the quats and phenols and other disinfectants -- we have don't work, we simply don't clean hospital environmental surfaces well enough. Dr. Philip Carling has conducted numerous studies that have shown that on average, at the time of terminal cleaning, only about 50 percent of surfaces have been touched. We have two options here. One option is to improve cleaning practices, ensure better education of housekeepers, use checklists so that environmental services personnel know exactly what to do. For example, Dr. Carling uses dots of fluorescent dye, marking surfaces and then shining a black light on these surfaces to see if the dots are still there, meaning they were not removed by the cleaning process and the cleaning was inadequate. The other option is using one of the new no-touch methods such as vaporized hydrogen peroxide or ultraviolet light. Dr. Rutala and I have published a paper on the efficacy of ultraviolet lighting, showing that 15 minutes of exposure to this light will kill MRSA, VRE and vegetative bacteria, and 50 minutes of exposure time will kill C. difficile. Dr. John Boyce has looked at vaporized hydrogen peroxide, showing again that it will kill MRSA, VRE and C. difficile. His is the first study to show that by using this kind of device you could actually reduce endemic rates of C. difficile in the hospital. That's a controversial area now as to how we improve terminal cleaning. Whatever the method, we know we must perform good daily cleaning, and most importantly, we need to get healthcare workers to perform proper hand hygiene. That's how we prevent the bugs from going from patient to patient. And also the proper disinfection of shared equipment such as thermometers, blood pressure cuffs -- the things that go from room to room.
Q: Do you think the new technologies supplant or supplement evidence-based practices relating to infection prevention?
A: Just as a general rule, any human factor analysis expert could tell you it's always better to re-engineer the system than to try to educate people about it. So for example, it's better to build cars with seatbelts and airbags, as telling people to be careful while driving will meet with only so much success. In healthcare, re-engineering systems is probably easier than trying to force people to alter their behavior. But since we don't have any perfect systems to do that yet, we must reduce HAIs by education and behavior modification in part with new technology. So ultimately, I believe the new technology will be useful. The question is, how do we decide to introduce this new technology? Just because we think something works doesn't mean it will. It is the job of the manufacturer to prove it works. For example, for a new drug to enter the market, the manufacturer must prove its efficacy and safety. For a medical device, only safety must be demonstrated. So before we accept expensive new innovations we must have proof that they are safe for patients and for hospital staff, but we need to see that they actually reduce infection rates. For instance, a study in JAMA showed that a chlorhexidine sponge will reduce central-line infections; so we have introduced it at UNC and our data supports that it does work. We introduced it first in our ICUs for a year, saw evidence of success, and then we introduced it hospital-wide. So we should demand that there is evidence of efficacy within well-designed studies that show that it works to truly reduce infection rates. In these days of cost-effectiveness consciousness, any innovation must demonstrate its value to the institution. With the caveat that they must be proved to actually work, these new technologies are tremendously exciting. In conjunction with the primary investigator, Dr. Sexton at Duke, we have received a CDC grant to study the effectiveness of these new room disinfection methods in a true randomized, controlled fashion. People are always showing us new technologies and our response is, 'Provide us with the scientific papers that demonstrate benefit.' and if they have science-based evidence that a new methodology will in fact reduce our HAI rates and it is cost-effective, then we consider it. Theoretically it's a zero sum game because if you spend money on that new methodology, it takes money away from something else. And we ought to spend money on things we know will work.
