THE CAUSE, EFFECT & SOLUTION TO BIOFILM CONTAMINATION OF DENTAL UNIT WATERLINES

Over the last months much has been published, said and demonstrated about the problem of Dental Waterline Biofilm. I, myself, had an article published on the subject back in June 2001 and was very pleased to see a back up article in September of the same year, in the same publication, from Dr Andrew Smith, BDS, PhD, FDS, RCS, MRCPath, Glasgow Dental Hospital 2.

 

It is now, without doubt, a scientific’ fact’ that in nature, if an opportunity arises because circumstances are correct, a microbial community of one sort or another will form 3. In dental unit water lines we have just such an example.

 

The nature of the tubing provides a carbon source for those microbes that use one, and water itself does for those that don’t, and it is possible that this is one of the reasons that they attach. The temperature of the surgery environment is ideal and the water flow such that it simply provides the microbes with fresh nutrient without exerting the level of pressure required to move even an ‘embryo’ biofilm layer. Added to this is the biggest problem. That being the surface area to volume ratio of the tubing. A relatively huge surface is available to the microbes for attachment.

 

 

As time progresses, the microbes develop into what can only be described as some sort of progressive community. It has now been stated in scientific papers 4 that communication channels are set up between microbial cells, and that these work in a similar way to hormones within the human body. The microbial chemicals generated and released by the exposure of one cell alert other cells within the community, and they in turn respond to the situation whether good, e.g a nutrient source or bad, e.g a chemical designed for their demise. As with any community approach, it is in their nature to either ‘go for it’ or ‘defend against it’.

 

Such is the complexity of life within a biofilm community that taken at a basic biological level, it very much seems to mimic our own human society. It should not then be too difficult to realise that, given a community happy with their lot and prepared to stand against whatever warfare is ‘flushed’ against them in order to keep their community in tact, Biofilm is a somewhat difficult problem to remove.

 

Of course there are casualties in the form of the top layer that sloughs off and presents as a gungy type of brown slime that prevents the water reaching the dental handpiece (see left). Other than being somewhat unpleasant, it must be irritatingly inconvenient. To add insult to injury, there is then the need to have the handpiece cleaned and serviced and in many instances this requires return to supplier or even manufacturer. The average cost of such an exercise should be borne in mind as well as the inconvenience and unless the original problem is treated effectively, the same will happen again. It’s nature’s way !

 

Research recently presented by the team from Porton Down 5 has illustrated that it is possible to reproduce a model of dental waterline biofilm under laboratory conditions. The very fact that such a model can be built and reproduced time after time further illustrates the fact that such Biofilms will and do exist. In addition, the same study also illustrated the relative effectiveness of the suggested treatments. These range from the simple ‘flushing’ of the system through generic chemical treatments to commercially available branded products such as the ALPRON + BRS Forte SYSTEM. The results speak for themselves but certainly illustrate that chemical treatment is the only plausible way to reduce and, with only a few products, remove the biofilm coverage, prevent its regrowth and minimise any increase in the microbial load of the water issuing from the line. The ALPRON + BRS Forte SYSTEM fell into this category.

 

The question remains, do these microbial communities pose a risk?

 

The answer has to be, potentially yes 6, particularly when one looks at the species of microbes generally associated with biofilm within a DUW, Psuedomonas Aeroginosa, Proteus Mirabilis, Leigonella sp to name but a few. There is also the possibility of colonisation of species generally found within the oral cavity as a result of the failure of anti retraction valves within the system. The risk of cross infection becomes even more of a potential risk of course when immuno – compromised patients are involved and in this day and age the numbers of patients within this category continues to steadily increase. In addition to this is the fact that waterborne microbes usually enter the body via the gastro – intestinal tract and this system has the defences needed to ward of any potentially infective agents entering by this route e.g the acidic conditions of the stomach, profusion of associated lymph nodes and resident white blood cells etc. In aerosol form from the handpiece spray, these potentially infective agents can enter the body via the respiratory system where the defences are designed more specifically to combat air - borne organisms.

 

It would  seem that, if these at risk patients, as well as the majority, are able to rely on the quality of the water from their taps at home, then at least the same quality should be delivered to them during dental treatment particularly if this involves any form of tissue damage that leads to blood loss, from scaling to  more involved surgical procedures. Added to this of course is the point that if, as guidelines suggest, handpieces are routinely autoclaved between patients, why then is microbially ‘super – charged’ water being run through them on the way to the patient ?

 

From the Practitioner’s point of view, of course, there are other issues still to consider, bearing in mind that as professionals, we all realise that the ultimate solution to the problem is to engineer it out by eliminating those physical features of the waterline that make it such an attractive habitat for microbes. Since these ‘new’ units don’t currently exist, the problem remains and we should be realistic enough to appreciate that, in the interim, precautions need to be taken to protect both the patients and the practice staff. This can be effectively achieved by treating the DUWs using the ALPRON + BRS Forte SYSTEM to remove the existing biofilm and then carrying out documented procedures to prevent it’s regrowth and at intervals check the quality of the water being delivered. In this way it can be shown that all possible precautions have been taken in order to minimise any potential risk to all concerned.

 

There is now a range of products available that allow the above to be possible to some degree or another but care should be taken in the choice, if the means is to justify the end result.

 

Any chosen product should have been proved to be clinically safe and have, at least for starters, a sound background of proven clinical data based on effectiveness against relevant standards i.e the more stringent European rather than U.S.A values and this should be readily available on request. In addition, the product should not have any effect on any procedures or materials used by the Practitioner.

 

From the Practitioner’s point of view the product has to be economically viable, easy to administer and quick to take effect in order to minimise the use of surgery and staff time.

 

Probably one of the most important aspects of any system is a method of monitoring that what has been implemented is still effective. This can be achieved by simply taking a microbiological count of the water within the lines, once every 3 months or so. Tap water quality should be the minimum acceptable.

 

As with all aspects of Infection Control, as it is panning out, effective cleaning and treatment procedures, auditing and recording of the audit results are the key to  all aspects of risk management of hygiene within the practice.

The ALPRON + BRS Forte SYSTEM fully incorporates ALL these parameters.

 

The general concensus of current thought, based on the wealth of scientific evidence available and the unfortunate experiences seen within other public sectors, is to accept that a problem exists with a potential, however minimal, risk and, until the required engineering is achieved, to be seen to be doing at least something to minimise that risk in order to show due diligence.

 

ASK ABOUT THE ALPRON + BRS Forte SYSTEM

 

References:

1. Dentistry, 21st June 2001.

2. Dentistry, 20th September 2001.

3. Watnick & Kolter, Journal of Bacteriology, May 2000.

4.Coghlan, New Scientist (Slime City), 31st August 1996.

5. Control of Planktonic & biofilm contamination in a laboratory dental unit water system, Walker, Bradshaw, Fulford, Martin, Marsh, March 2002.

6. Microbial Biofilm formation and Contamination of Dental Unit Water Systems in General Dental Practice, walker, Bradshaw, Bennett, Fulford, Martin, Marsh, Applied & Environmental Microbiology, August 2000.

 

 

Written by:

 

Jayne Warren B.Sc (Hons) Medical Sciences sp. Medical Microbiology, PGCE

Partner, Quality Water Specialists LLP.

June 2002

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