The Trojan Horse

Trojan_horse_ÇanakkaleI’ve been mulling over the issue of sinks in clinical areas a lot recently and a paper published today in the Journal of Hospital Infection has really crystallised my thoughts. Sinks are everywhere; often extra ones are installed in the quest for high hand hygiene compliance however are we really thinking about the risks that these may cause apart from the traditional ones posed by Pseudomonas and Legionella? Do we even really reflect upon what they are used for?

I really like this paper by Grabowski and colleagues from Virginia in which motion-sensitive cameras monitored activity at four sinks over 60 days, generating 4810 videos, 38% of which were false-positives of activity by the sink. From the remaining videos, over five and a half thousand activities were examined for activity type. Hand hygiene comprised 4% of all activities, the lowest of any form of sink-related activity. Importantly, the authors looked at the fluids that were entering the sink, with soft drinks and juices being the most common however IV fluid bags were also emptied down the sink. This ceaseless supply of nutrients is what feeds sink biofilms as demonstrated superbly in a paper published in Applied Environmental Microbiology last year, in which Green Fluorescent Protein (GFP) Expressing- Escherichia coli were used to demonstrate two things. Biofilm formation and spread within plumbing systems and importantly, the extent of dispersal from a contaminated sink. The researchers found that if only water were run into the sink for 14 days, organisms remained contained in the p-trap, however once nutrients were periodically added, biofilm ascended the pipework at a rate of 2.5cm/day until the strainer was reached just 7 days later. The result of the strainer becoming contaminated meant that when the sink was accessed, droplets were dispersed to the surrounding area, including the area in which the person would be using the sink were standing and the tap area. Interestingly, the artificially contaminated sink was set up as one of six, three each side of a central drain. Five of the other sinks then became contaminated and the only one that was not within the duration of the study had the highest rise, so possibly only a matter of time.

The upshot from these two studies is that current practice is that staff are regularly providing all of the nutrients required to maintain a healthy population of gram-negative bacteria with the potential to disperse in a clinically meaningful manner. Thrown into the mix is the study from Prof. Peter Wilson’s group at University College London which demonstrated transfer of resistance genes within these plumbing systems.

So what to do? Good question! Well a couple of brave souls have taken the sink out of play altogether by going water-free, a report from Spain seeking to control endemic gram-negatives and a paper from the Netherlands that I previously blogged, where an increase in resistant Enterobacter cloacae was a problem demonstrating promise in terms of reducing gram-negative colonisation that became more pronounced with extended stay. When presenting this study as one of my favourite papers at a meeting earlier this year, I wondered what the staff might think of sink removal however this recent study has shown that with hand washing at a sink comprising the lowest activity maybe they wouldn’t miss it from a hand hygiene perspective now that alcohol hand rub, available at the point of care has become so established. So the question is – are sinks beneficial or are there risks contained within?


8 thoughts on “The Trojan Horse

  1. Another possibility: The water of the sinks are used in addition to the hand hygiene of healthcare workers to carry out the body hygiene of bedridden patients, particularly in ICUs. Probably this is the source of GNB colonization (MDR or not) of the patients, from the water contaminated by the splash of the sinks, not through the hand washing of the healthcare personnel.

    Liked by 1 person

      • Totally agree Martin. I just presented A Year in Infection Control at ECCMID and talked about the healthcare environment. Both the Netherlands and the Spanish publications have shown a reduction in Klebs and Pseudomonas HAI.We removed our sinks from clinical areas (NNU in particular) a year ago and this had a major impact on MDRO.

        Liked by 1 person

  2. Thank you for sharing this with us! Is really good to realise!
    I tried to open the links in the blog, but they didn’t work. Could you provide me with the details of the articles mentioned?

    Many thanks!

    Liked by 1 person

  3. Sigh. Rule # 1. Never scale a bad system. Rule #2. Don’t throw out the baby with the bath water.

    Staff are told not to dispose of anything down the sinks. But they do. Signs are posted. They still do. Why do we continue to expect compliance from humans? They will disappoint you every time. When given the choice of whether to rely on human compliance or technology, choose technology.

    Following this advice, sinks dispensing raw untreated water, and sinks with no engineered means of protection from biofilm and aerosolisation of bacteria and fungus should never be installed in hospitals. Either eliminate the sink, or use only self-disinfecting sinks. Given that ABHR is not sporicidal, I would choose the latter.
    It’s not rocket science…or medicine…it’s just common sense and engineering.

    Liked by 2 people

  4. I remember an outbreak once whilst working in Nottingham and when they were designing the new purposed build unit they installed waste trap heaters on all sinks to prevent build up. Sinks always concern me as they are always used for other things despite notices etc and where do we put the glove and apron dispenser, right next to them, leaving them open to potential contamination from aerosolization.

    Liked by 1 person

  5. ‘Design’ rather than just expecting ‘compliance’ would be helpful.

    1. No sinks should be placed or even be visible in the common areas of the hospital. For the emergency drainage of liquids, if required, some suction/ vacuum system may be rather installed or made available.

    2. The dissemination of pathogens through aerosols generated may be reduced by appropriate air circulation/ ventilation design that effectively removes the aerosols generated from the common crowded areas before they get inhaled or may contaminate other surfaces. Additional protective equipment (e.g., masks) usage may be also enforced in more sensitive areas.

    3. The separation and isolation of hospital sewage system from the general sewage system should be also enforced by design, where the waste water from hospital sewer system is never allowed to mix with general public sewage system at any point of time rather always treated separately. It could help decrease the basal rate of dissemination/appearance of the drug resistance among microbes in the environment and the appearance of pathogens.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s