A key review article has been published in the Journal of Hospital Infection summarising the accumulating evidence that the status of the prior room occupant can influence the chances of the incoming occupant picking up an MDRO. The bottom line is that if you are admitted to a room previously occupied by a patient with an MDRO (including MRSA, VRE, C. difficile and Acinetobacter sp.), you are twice as likely to acquire that MDRO. The impact of these findings is clear: we need to improve standards of discharge disinfection to protect the incoming occupant. So how can we do this? There are several paths to follow towards the same end – and these are not mutually exclusive:
Improve the cleaning / disinfection process
The advent of fluorescent markers and other similar approaches has provided the tools for us to “demystify” the cleaning / disinfection process, and provide hard evidence as to whether or not surfaces are being cleaned. ‘Performance managing’ this process can result in impressive improvements (although data are awaited eagerly on improved patient outcomes).
Developing new modalities to make cleaning / disinfection easier
The emergence of disinfectant wipes solves a number of important challenges to cleaning and disinfection: correct formulation, no risk of contaminating a cleaning solution, and – perhaps most importantly – convenience.
Producing novel disinfectants
As our understanding of the importance of biofilms on hospital surfaces evolves, the need for disinfectants formulated specifically with anti-biofilm activity in mind is clear. Gama is working towards this end through a partnership with Cardiff University.
Poorly designed hospital surfaces that are difficult (or impossible!) to clean can be addressed through improved design (check out Gama’s easy-clean commodes and keyboards).
Reduced patient shedding
One way to reduce the level of environmental contamination is to control the shedding of MDROs from patients through regular chlorhexidine bathing. This has been shown to reduce the level of skin and environmental contamination, and improve patient outcomes.
An attractive approach is to somehow make surfaces antimicrobial to continuously reduce the levels of contamination. There are various options to achieve a similar aim, and some evidence that patient outcomes may be improved.
Automated room decontamination (ARD)
ARD systems reduce or remove reliance on the operator to assure adequate distribution and contact time of the active agent. There is accumulating evidence that these systems (both HPV and UV) protect incoming occupants from the increased risk from the prior room occupant. In high risk settings, it is becoming increasingly clear that these systems will become the standard of care in coming years.
It is difficult to know which of the above approaches to prioritise since comparative data on the relative impact of these methods is almost non-existent. But we need to find a way to improve the standards of discharge disinfection one way or another!
There is a general feeling that being antibiotic resistant imposes a considerable fitness cost for bacteria – and the more resistant, the less fit the bacterium becomes. Whilst this is no-doubt true to some degree, a recent study from Brazil shows that MRSA, MSSA and vancomycin-intermediate S. aureus (VISA) have very similar survival properties on dry surfaces.
One strain of MRSA, MSSA and VISA were dried onto various surfaces and survived for a similar length of time. In general, S. aureus survive better on non-porous surfaces than on porous surfaces – and VISA ‘out-survived’ the MRSA and MSSA strain on the non-porous surfaces. However, VISA didn’t do so well on the porous surfaces, surviving for less time than MRSA and MSSA. Previous studies have suggested that VISA are better at forming biofilms than other S. aureus. This was tested, but did not seem to be the case ‘ the MRSA strain seemed to be the most effective biofilms producer.
However, since only one strain of each type was tested, it is difficult to be certain of any comparisons. Previous work has illustrated considerable strain variation in the survival properties of S. aureus, so it’s a shame that more strains were not included for each group. Nonetheless, the study shows that even highly antibiotic-resistant S. aureus retains the ability to produce biofilm and survive on dry surfaces for extended periods.
There is a general view that bleach is a well-proven intervention to prevent the transmission of pathogens associated with HCAI, especially C. difficile. However, a systematic review from some Spanish researchers highlights the limitations of the evidence base. Importantly, the review highlighted the limitations of bleach in dealing with dirty surfaces, which inactivate the bleach to a surprising degree, and surface-dried viruses, which exhibit considerable reduced susceptibility to bleach. Other disinfectants are also likely to suffer reduced susceptibility when dealing with dirty surfaces, and surface attached microbes, but it does seem that bleach is particularly sensitive to inactivation by dirty surfaces.
The review identified only four studies that evaluated the impact of introducing bleach as a single intervention to prevent cross-transmission (Orenstein, Hacek, McMullen, and Wilcox). Bleach was commonly implemented in tandem with other interventions, but these were not eligible for inclusion because it is not possible to determine the relative contribution of each. It was a surprise not to see the Mayfield study included in this review; it must have slipped through the inclusion criteria somehow. Also noteworthy that one of these studies (Wilcox) showed that bleach was ineffective when the pre-planned cross-over occurred, suggesting that other factors were also involved in the rate of C. difficile infection. The plan was to perform a meta-analysis of the available studies, but this was not possible due to the variable structure and quality of the studies – not least the concentration of bleach used.
This review certainly did not conclude that bleach is ineffective and presented some useful data that implementing bleach can help to reduce the transmission of hospital pathogens. However, the evidence-base for using bleach is not as strong as you may think, and further studies are required to explore the clinical impact of bleach and other options for hospital surface disinfection.
Another abstract published at the recent ID Week meeting (on page 13)* in the USA has added to the burgeoning collection of studies that indicate that the routine use of UV-C disinfection of clinical areas carries a clinical benefit. The paper from David Pegues and colleagues from the University of Pennsylvania examined the effect of UV-C as part of terminal disinfection on inpatient units that had a persistently high rate of Clostridium difficile infection (CDI) despite multiple interventions.
The study was carried out over a one-year period in three haematology/oncology units totalling 75 mostly single-bedded rooms. All rooms housing patients with either CDI or who were on contact precautions were disinfected using a UVDI machine that is marketed in the UK by Gama Healthcare as the UV-360. Two machines were used over the year and a total of 542 rooms were disinfected using this method (21% of all discharges). Impressively, the use of this machine for two 8-minute cycles in each room did not necessitate any increase in staffing requirement- for the adoption of this measure.
Analysis of data from the intervention year when compared with the previous year demonstrated a significant association between the use of the UV-C and a decline in CDI on the study units, whereas rates increased on the non-study units. Hopefully the authors of this abstract will submit a full paper to a peer-reviewed journal so that fuller information about the conduct of the study can be shared, however the conclusions of the authors are unequivocal; The targeted use of UV-C resulted in a substantial reduction in CDI with no adverse effect on room turnaround. Read it the paper online here
The largest ever study of an automated room decontamination (ARD) device has just been presented at a conference in the USA. The CDC Epicenters funded collaboration between Duke, UNC and some other US hospitals evaluated the impact of a UVC room disinfection device compared with standard approaches to terminal room disinfection. The bottom line is that UVC disinfection reduces transmission.
The study hypothesis was that if admission to a room previously occupied by a patient with a multidrug-resistant organism (MDRO) increases the chances of the incoming occupant acquiring that MDRO, then doing a better job of terminal disinfection ought to mitigate the increased risk. There is evidence from two other studies that this hypothesis makes sense: one study showed that improving conventional methods reduced the risk for the incoming occupant for MRSA (but not for VRE), and another study showed that patients admitted to rooms decontaminated using hydrogen peroxide vapour were 64% less likely to acquire an MDRO.
UVC is an attractive approach because it is easier to implement and faster than hydrogen peroxide, and more reliable than conventional methods because it does not rely on the operator to assure distribution and contact time. Which is why the results of this landmark study are so crucial. The randomised study was performed over more than 2 years across 9 hospitals and included more than 25,000 exposed patients (admitted into a room where the previous occupant was known to have an MDRO). Each hospital performed a randomised sequence of different terminal room disinfection approaches: quaternary ammonium compound (QAC) disinfection (control group), bleach, QAC+UVC, and bleach+UVC. The primary outcome was the acquisition rate of a composite group of MDROs (MRSA, VRE, C. difficile, and MDR Acinetobacter species).
Compared with the control group, patients admitted into a room decontaminated using UVC were significantly less likely to acquire an MDRO; this difference was 37% (p=0.03) when rooms were pre-cleaned using QAC, and 32% (p=0.01) when rooms were pre-cleaned using bleach (see Figure below). Surprisingly, patients admitted to rooms disinfected using bleach were not significantly less likely to acquire MDROs compared with the control group (p=0.08).
Figure: The relative rate of MDROs follow enhanced terminal disinfection compared with a control method (QAC disinfection)
The powerful, randomised study design makes it very unlikely that these results are explained by anything other than the improved environmental reductions achieved by UVC compared with conventional methods. The take home message is this: UVC should now be used as an adjunct for the terminal disinfection of rooms vacated by patients known to be infected or colonised with an MDRO!