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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
is a collection of microorganisms (bacteria, algae, and man-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 adhesive matrix (slime). and 45°C.
Various studies have shown that, In Europe, - stagnant water and the presence
regardless of the material used Australia and the USA, of other microorganisms capable
1: Cell attachment (copper, CPVC, stainless steel, of providing nutrients that its own
polypropylene, etc.), biofilm forms approximately metabolism is unable to produce,
systematically after several weeks or 1 015 in addition to scale or corrosion.
months even on biocidal materials. Human contamination occurs
cases are detected per million via the respiratory route (inhaling
99.5% of bacteria found in these in habitants per year contaminated water in aerosol format)
installations are trapped in the biofilm, Source: and can lead to a serious pulmonary
which provides the ideal environment World Health Organisation infection: legionellosis.
(water, temperature and nutritional
conditions) for them to proliferate.
If the conditions are favourable, the bacteria multiply LEGIONELLA REGULATIONS:
2: Irreversible cell attachment and form aggregates that can easily become detached
and contaminate the water supply. A COMMON APPROACH
Biofilm is impossible to eradicate, but its
development can still be controlled. Legionella monitoring and prevention are governed
by different regulations around the world. Although
Bacteria in the BIOFILM Free-floating bacteria standards vary from country to country, they are
BIOFILM
99.5% 0.5% generally based on common principles aimed at
limiting the proliferation of Legionella pneumophila
and protecting public health.
Monitoring water systems
High-risk facilities such as drinking water systems are
3: Biofilm maturation phase I
regularly monitored. Samples and analyses are carried
out to detect the presence of Legionella bacteria and
assess their concentration.
THE FIGHT AGAINST
Application of regulatory thresholds
WATERBORNE BACTERIA and implementation of risk management plans
The health authorities define Legionella concentration
Infection control must be the priority for healthcare thresholds that must not be exceeded. When these
facilities, which shelter many germs such as viruses thresholds are reached or exceeded, corrective
and bacteria. measures must be put in place, such as disinfecting
There are two types of waterborne bacteria which are installations or changing water management
4: Biofilm maturation phase II responsible for healthcare acquired infections parameters. The regulations also encourage
in hospitals: the implementation of risk management plans,
- bacteria in the system which develop when in contact incorporating preventive action, monitoring and
with water e.g. Legionella spp. intervention in the event of contamination.
- bacteria at the point-of-use (water controls)
which develop when in contact with air/water e.g. In Australia, for example, the standard AS/NZS
Pseudomonas aeruginosa, Mycobacterium avium, 3896:2017 defines the methods for detecting and
Mycobacterium xenopi, etc. quantifying Legionella in water.
Since these two types of bacteria are very different, In the UK, the Health and Safety Executive (HSE)
bacteriological monitoring must be appropriate imposes strict obligations with the L8 Approved Code
for both types. of Practice, which details measures for preventing,
monitoring and controlling Legionella in water systems.
5: Cell dispersion In the European Union, the Directive 2020/2184 on
the quality of water intended for human consumption
Source: Chinks in the Armor requires Member States to monitor Legionella in
of Bacterial biofilms Monroe drinking water systems, while the EN ISO 19458
D PLoS Biology Vol. 5, No. 11, specifies water sampling methods for Legionella control.
e307 doi: 10.1371/journal. In Canada, the Canada Labour Code requires
pbio.0050307/D. Davis.
employers to prevent exposure to Legionella.
For its part, Health Canada recommends monitoring
thresholds and suggests sampling protocols.

4 Hospital solutions