HIS Spring Meeting: ‘Contaminated surfaces: the missing link’


Thought I’d share some key points from the 2016 HIS Spring Meeting.

Outlining the problem(s)

Prof Gary French kicked off the meeting with a (sic) historical perspective, describing how the perceived importance of the environment in transmission has oscillated from important (in the 40s and 40s) to unimportant in the 70s and 80s to important again in the 2000s. Gary cited a report from the American Hospital Association Committee on Infections Within Hospitals from 1974 to prove the point: ‘The occurrence of nosocomial infection has not been related to levels of microbial contamination of air, surfaces and fomites … meaningful standards for permissible levels of such contamination do not exist.’ Gary covered compelling data that contaminated environmental surfaces make an important contribution to the transmission of Gram-positive bacteria and spores, highlighting that C. difficile in particular is a tricky customer, not helped by the fact that many ‘sporicides’ are not sporicidal!

Next, Martin Kiernan gave an overview of the role of contaminated surfaces in the transmission of Gram-negative bacteria. Although it is clear that contaminated surfaces contribute to the transmission of resistant Gram-negs, this is such a heterogeneous group of bacteria that the degree to which contaminated surfaces contributes is likely to vary by genus and species. For example, emerging evidence suggests that A. baumannii is ‘more environmental’ than E. coli. Finally, we need to understand the importance of air contamination, the spread of resistance genes in environmental Gram-negs, and the contribution of biofilms.

Then, Dr Jake Dunning used norovirus and MERS-CoV as illustrations of the importance of surface contamination in the spread of viruses. There are several important stands of evidence that point towards an important role for contaminated surfaces in virus transmission including lab studies, human / animal trials, epi investigations, modelling, and intervention studies. However, despite the fact that most accept that contaminated surfaces play a key role in the transmission of norovirus, the evidence-base is fairly sparse. I am convinced though – and Jake pointed me to this recent study showing a very high level of norovirus environmental contamination in a hospital ward (around 50% of environmental samples were PCR+ for norovirus). Recent data suggests that MERS-CoV is in the more-environmental-than-you-may-think club, along with its counterpart SARS-CoV. I recently review the evidence that contaminated surfaces play a role in the transmission of respiratory viruses, and although circumstance will dictate which is the most important transmission route, I think it’s fair to conclude that environmental surfaces are probably more important than we realise in virus transmission!

Discussing the solution(s)

Having established that environmental surfaces do indeed make an important contribution to nosocomial transmission, the rest of the day was spent discussing how to approach this problem.

  • Dr Tim Boswell reviewed the evidence that ‘source control’ can be a useful strategy to reduce the degree of pathogen shedding into the environment.
  • Dr Jimmy Walker considered the potential advantages and evidence-base for introducing antimicrobial surfaces.
  • Prof Peter Wilson discussed the pros and cons of the various objective measures to monitor the manual cleaning process (visual v microbiological v ATP v fluorescent marker evaluation of hygiene. (See useful AHRQ review here.)
  • Prof Jean-Yves Maillard scanned the horizon for new disinfectants, covering new ‘green’ synergies (e.g. H2O2 + PAA), limitations of residual activity, and the need for anti-biofilm formulations.
  • Tina Bradley was given the unenviable title (by me!) of ‘Endoscopes: Managing risk from complex items that go where the sun don’t shine’. Ensuring a safe supply of endoscopes is a minefield of design, risk and complexity!

The day concluded with a debate between Peter Hoffman and yours truly on whether ‘Automated disinfection provides more effective infection prevention than manual disinfection’. I was putting forward the pro argument that we have a problem we need to fix (illustrated by the prior room occupant data), manual systems are doomed to failure, automated room decontamination (ARD) systems work, and they are cost effective and feasible. (You can download my slides here.) Peter countered by highlighting the probability of a bias toward ARD positive studies, some of the fundamental limitations of UV-based ARD systems, and critiqued beautifully a number of HPV studies. Despite what I thought was a cast-iron position for me, I was disappointed to see that exactly half of the audience agreed with Peter! Oh well, a draw was probably a fair result on balance. In all seriousness though, I hope the debate highlighted that we need to both improve existing manual processes, and consider carefully the adoption of ARD systems to augment manual processes in some clinical scenarios.

I was privileged to be asked to put together the programme for the day, and I’m pleased to say that all of the speakers were excellent, the day was over-subscribed, and there seemed to be a buzz in the room. Congratulations to HIS for putting together such a stimulating meeting, and thanks to all who participated as delegates, speakers, and exhibitors).

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