Advertising feature
Is your water safe?
Clare Clark, BSc (Hons) Microbiology, technical support manager, schülke UK
D
ental unit waterlines (DUWLs) are a key focus for infection control, as they are easily contaminated with microorganisms, leading to
biofilm development. Technological advances in disinfectants mean the threat can be virtually eradicated by best practice.
How safe is your water? The water in DUWLs contains high numbers of bacteria. Some is swallowed by the patient and droplets may be inhaled by staff. A study of DUW systems showed that in 95 per cent of water samples, microbial loading exceeded EU drinking water guidelines. The authors believe these ‘values probably underestimate the true microbial load to which a patient is exposed’. The most common pathogen found was Pseudomonas spp. Legionella pneumophila, Mycobacterium spp. and Candida spp. were also detected.
DUWL and biofilm formation The source of bacterial contamination in DUWLs is due to micro-colonies of proliferating microorganisms on the inner surface of water lines. Frequent periods of water stagnation, and the properties of the plastics from which they are manufactured, promote attachment and colonisation of
biofilm-forming microorganisms. Biofilms form along the inner surface of DUWLs and water flowing down the biofilm-coated water lines contributes to microbial load in water exiting the tubing. Biofilms protect organisms from the effects of chemicals, reducing their susceptibility to disinfectants.
Regulations and guidance The Combined Practice Inspections (CPI) checklist came into force in Scotland in 2013 and all essential Category A criteria must be met. Section 3ı6 of the CPI checklist states ‘a biocidal’ should be ‘used to flush water lines’. This Category A item is a mandatory part of the inspection. It is reasonable to expect water quality
to meet the same standards as drinking water – the European standard for drinking water is less than 100 CFU (colony forming units). Once water enters the DUWLs, bacteria increases, with numbers as high as ı.6 x ı05 CFU ml-ı having been recovered.
Biofilm control Although water lines should be flushed ‘between patients’, studies show this alone results in only a small reduction in biofilm TVC (9.ı per cent) and an even smaller reduction in biofilm coverage (0.5 per cent). A study evaluating a range of disinfectants to control biofilm contamination
states a number of criteria must be fulfilled: • Killing of bacteria in the water phase • Killing of biofilm bacteria • Removal of biofilm from surfaces Biofilms need to be removed as well as
‘killed’, as a ‘killed’ biofilm could still act as a source of endotoxins, allowing rapid recolonisation of new biofilm.
schülke watersafe A study of disinfectants found most did not meet all criteria. However, schülke watersafe (previously schülke DUWL) provides complete elimination of viable bacteria and 100 per cent reduction of biofilm coverage. Biofilm regrowth after disinfection occurs within seven to ı4 days, suggesting weekly treatment programmes are not sufficient to cut microbial counts. schülke watersafe provides a one-off initial treatment to completely remove biofilm, followed by a continual dosing regime to protect against regrowth. An additional advantage is that schülke water- safe is approved for routine use in DUWLs.
Conclusion Safe dental treatment requires good quality water. schülke watersafe disinfectant is a major weapon in total biofilm removal together with a maintenance programme in an easy-to-use application.
® For further information, contact Allan Wright, schülke, 07976 513439
Scottish Dental magazine 67
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