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/ Infection control


              Stages in the development   CONTROLLING BIOFILM                LEGIONELLA
              of biofilm on a surface

                                   Naturally present in mixers, taps and pipework, biofilm   This bacteria lives naturally in fresh water and man-
                                   is a collection of microorganisms (bacteria, algae,   made water features.
                                   fungi, etc.) adhering to each other and to surfaces    For optimal development Legionella requires 2 main
                                   that are generally in contact with water, and which    elements:
                                   is characterised by the secretion of a protective    - water at a temperature between 25°C and 45°C.
                                   and adhesive matrix.                        - stagnating water in the presence of scale or rust.
                                   Various studies have shown that, regardless      Infections are contracted via breathing
                                   of the material used (copper, CPVC,               (inhaling contaminated water in aerosol
              1: Cell attachment   stainless steel, polypropylene, etc.),             format) and can lead to a serious
                                   biofilm forms systematically after    495           pulmonary infection: Legionellosis.
                                   several weeks or months even on   cases of Legionnaire’s
                                   biocidal materials.               disease in the UK
                                                                                       MONITORING
                                                                     Source: ECDC (European Centre
                                   99.5% of bacteria found in these    for Disease Prevention    FOR LEGIONELLA SPP.
                                                                        and Control), 2017
                                   installations are trapped in the biofilm,
                                   which provides the ideal environment (water,
                                   temperature and nutritional conditions) for them   The Health and Safety Executive (HSE) guidance
                                   to proliferate.                           for the control of Legionella bacteria in hot and cold
                                   If the conditions are favourable, the bacteria multiply   water systems states that monitoring for Legionella
              2: Irreversible cell attachment  and form aggregates that can easily become detached   should be carried out:
                                   and contaminate the water supply.         - when water is treated with biocides or when distribution
                                   Since biofilm is impossible to eradicate, healthcare      temperatures are reduced from HSE guidelines.
                                   facilities must do everything in their power to limit   - where water treatment regime control levels are not
                                   bacterial proliferation.                    being consistently achieved.
                                                                             - where there is a high-risk of contamination e.g.
                                     Bacteria in the BIOFILM    BIOFILM  Free-floating bacteria     hospitals and care homes.
                                          99.5%                  0.5%        - where an outbreak of Legionellosis has been identified.
                                                                              (Source: HSG274 part 2 published in 2014).

                                                                               Monitoring levels for Legionella spp.:
              3: Biofilm maturation phase I                                         Alert level         < 100 CFU/L
                                                                                                        > 100 CFU/L
                                                                                  Remedial action     up to 1,000 CFU/L
                                                                                   Curative action     > 1,000 CFU/L
                                                                               CFU/L: Colony forming units/Litre
                                   THE FIGHT AGAINST
                                   WATERBORNE BACTERIA                       For high-risk patients in hospitals the draw-off
                                                                             at the point-of-use should always be free
                                                                             from Legionella spp. bacteria.
                                   Infection control must be the priority for healthcare
                                   facilities, which shelter many germs such as viruses
                                   and bacteria.
              4: Biofilm maturation phase II  There are two types of waterborne bacteria which are
                                   responsible for healthcare acquired infections
                                   in hospitals:
                                   - bacteria in the system which develop when in contact
                                    with water e.g. Legionella spp.
                                   - bacteria at the point-of-use (water controls)
                                    which develop when in contact with air/water e.g.
                                    Pseudomonas aeruginosa, Mycobacterium avium,
                                    Mycobacterium xenopi, etc.
                                   Since these two types of bacteria are very different,
                                   bacteriological monitoring must be appropriate
                                   for both types.
              5: Cell dispersion

              Source: Chinks in the Armor
              of Bacterial biofilms Monroe
              D PLoS Biology Vol. 5, No. 11,
              e307 doi: 10.1371/journal.
              pbio.0050307/D. Davis.










              4   Hospital solutions
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