Ebola: PPE and paranoia

The contrast in the stringency of the CDC and UK Department of Health / Health and Safety Executive guidelines for infection prevention and control when dealing Ebola virus disease (EVD) patients is striking. This is particularly acute with regard to recommendations for Personal Protective Equipment (PPE) and terminal disinfection. Having recently reviewed both documents for a webinar on Ebola infection prevention and control (you can download the slides here, by the way), I thought I’d share the contrast:

Table: PPE and disinfection recommendations for dealing with patients with Ebola virus disease. Source: US CDC patient and environmental guidelines, and UK Department of Health. (Please note – this summary chart is designed to be illustrative rather than definitive.)Ebola ppe table

So is there any reason why the level of PPE and type of terminal disinfection required should be any different depending on which side of the Atlantic you happen to be? None whatsoever. So why the discrepancy? It’s difficult to say. This difference in recommendations has prompted the question of “To CDC or not to CDC” in terms of PPE for Ebola, and an opinion piece in Annals of Internal Medicine justifying the CDC approach. It is probably true that the level of PPE recommended by CDC is enough to block transmission, and that the risk of environmental contamination is low enough such that fumigation is not necessary. Probably. But is that good enough when Ebola is on the line? It is certainly true that you can be wearing all the PPE in the world but if you put in on incorrectly, don’t take care of it during use or remove it carelessly you will put yourself at risk.

When I came to decontaminate a room using hydrogen peroxide vapour following a case of Lassa fever in London some years ago, I wore all the PPE that I could lay my hands on (see below)!

Me illustrating the “belt and braces” (aka paranoid) approach to PPE (a la UK, not CDC recommendations).Lassa PPE me_annotated

Did this level of PPE match the risk of exposure to viable Ebola? Perhaps not, but it certainly made me feel a whole lot more secure about entering the room to do the job!

Is it time to turn to ‘no-touch’ automated room disinfection?

I gave a webinar for 3M yesterday entitled ‘Is it time to turn to ‘no-touch’ automated room disinfection (NTD)?’ It was based broadly on a recent Journal of Hospital Infection review article, and you can access the slides here.

The webinar covered:

  • The key data supporting the need for improved hospital disinfection, particularly ‘terminal disinfection’ when patients are discharged.
  • The strengths and limitations of conventional disinfection methods, particularly in terms of reliance on the operator to ensure adequate formulation, distribution and contact time of the active agent.
  • The potential benefits of introducing automation into the room disinfection process.
  • Coverage of the advantages and disadvantages of the various “no-touch” automated room disinfection systems currently available.
  • Scenarios in which NTD systems may be warranted.

To summarize the rationale for using an NTD system: enhanced conventional methods are able to eliminate pathogens from surfaces, but the inherent reliance on a human operator to ensure adequate formulation, distribution and contact time of the active agent introduces variability into the process. NTD systems remove or reduce reliance on the operator for delivering hospital disinfection. However, they do not obviate the need for cleaning, so they are designed to augment rather than replace conventional methods.

So when to consider an NTD system? The flow chart below (Figure 1) shows a decision tree for which cleaning and disinfection approach to take. Given their practical limitations, NTD systems are best suited to disinfection of a room after a patient colonized or infected with a pathogen has been discharged to protect the incoming patient from acquiring the pathogen left behind by the prior room occupant. A recent study of a hydrogen peroxide vapor (HPV) NTD system shows that patients admitted to rooms disinfected using HPV were 64% less likely to acquire any multidrug-resistant organism (MDRO) than patients admitted to rooms disinfected using standard methods when the prior room occupant had an MDRO.Flow chartFigure 1. A disinfection decision diagram for when to consider an NTD system. a) Key pathogens associated with contamination of the environment include C. difficile, VRE, MRSA, A. baumannii, P. aeruginosa and norovirus. b) All NTD systems are applied after a cleaning step to ensure that surfaces are free from visible contamination, which is unacceptable to subsequent patients and will reduce the efficacy of the NTD disinfection. c) There is limited equivocal evidence that enhanced cleaning / disinfection in a low-risk general ward setting can reduce the spread of pathogens.

Ok, so you’ve decided that you want to use an NTD system. Which one to choose? Every conference I go too seems to have more and more NTD systems on show, all with bold and often conflicting claims. There are essentially four classes of NTD system that are commonly used in hospitals:

  • Hydrogen peroxide vapor (HPV)
  • Aerosolized hydrogen peroxide (aHP)
  • Ultraviolet C (UVC)
  • Pulsed-xenon UV (PX-UV)

I asked the audience which, if any, NTD system had been used in their hospital (Figure 2). 90% of the predominantly US based audience had not used an NTD system at all, which was a surprise. In the hospitals that had used an NTD system, there was a fairly even split between HPV and the UV systems.Which systemFigure 2. Has your hospital used an NTD system and if so, which one?

Each of these systems have advantages and disadvantages, which I have tried to summarize in the following table by ranking the systems in the key categories. The hydrogen peroxide systems tend to have higher efficacy and better distribution than the UV systems. But the UV systems are faster and easier to use. Thus, there is a trade-off between efficacy / distribution and cycle time / ease of use when deciding which NTD system would be more appropriate.Comparision table Table: Comparing the key features of the four commonly used NTD systems.

In order to illustrate the challenges in choosing a) whether to use and NTD system and b) which to use, I presented the audience with three scenarios. In scenario 1, below, I was expecting most people to select ‘conventional methods’ or one of the UV systems, which have both been shown to reduce the burden of contamination without reliably eliminating pathogens. The sheer number of patients with MRSA colonization transferred or discharged from general medical wards means that the additional time for HPV may not be warranted.Scenario 1Scenario 1. What do you do when a patient who was colonized with MRSA has been discharged from a room on a general medical ward?

Scenario 2 is an occasion where you want to be sure that residual contamination has been dealt with so that the incoming susceptible ICU patient will not acquire the virtually untreatable carbapenem-resistant A. baumannii. Therefore, HPV, which is associated with the elimination of pathogens from surfaces, is a rational choice.   Scenario 2Scenario 2: What do you do when a patient who had an infection with carbapenem-resistant A. baumannii has been discharged from an ICU room?

Scenario 3 is more tricky. While the likelihood of C. difficile spore contamination argues for the higher efficacy of the hydrogen peroxide systems, the number of transfers or discharges of patients with C. difficile on a surgical unit may be high, which argues for the lesser efficacy but faster cycles from the UV systems. The majority of the audience selected HPV in this scenario, considering that the combined risk of the pathogen and specialty required the elimination of C. difficile spores from the room prior to the admission of the next patient.    Scenario 3Scenario 3: What would you do when a patient who had C. difficile infection has been discharged from a room on a surgical unit?

To summarize, the use of an NTD system to augment terminal disinfection is warranted in some circumstances. The choice of NTD system will depend on a number of factors, including efficacy, distribution, ease of use, cycle time and cost. The features of the various NTD systems make them best suited to different applications, dictated by the clinical setting and the environmental-pathogenic characteristic of the target pathogen. So, is it time to turn to NTD systems? 52% of the audience voted ‘yes’ at the start of the webinar; 74% voted ‘yes’ at the end!Initial finalFigure 3: Is it time to turn to ‘no-touch’ automated room disinfection? The audience were asked this question at the start and the end of the webinar, indicating a swing towards the affirmative!

Article citation: Otter JA, Yezli S, Perl TM, Barbut F, French GL. Is there a role for “no-touch” automated room disinfection systems in infection prevention and control? J Hosp Infect 2013;83:1-13.