Page 6 - Water_Controls_for_Healthcare

/ 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 45°C.
and adhesive matrix (slime). - stagnant water and the presence of other
Various studies have shown that, regardless of microorganisms capable of providing nutrients
the material used (copper, CPVC, stainless that its own metabolism is unable to
1: Cell attachment steel, polypropylene, etc.), biofilm forms produce, in addition to scale or corrosion.
systematically after several weeks or 517 Human contamination occurs via the
months even on biocidal materials. cases of Legionnaire’s respiratory route (inhaling contaminated
disease in the UK water in aerosol format) and can lead
99.5% of bacteria found in these Source: ECDC (European Centre to a serious pulmonary infection:
installations are trapped in the biofilm, for Disease Prevention legionellosis.
which provides the ideal environment and Control), 2019
(water, temperature and nutritional
conditions) for them to proliferate. MONITORING FOR LEGIONELLA
If the conditions are favourable, the bacteria multiply
and form aggregates that can easily become detached
2: Irreversible cell attachment and contaminate the water supply. The United Kingdom, France, Germany and the
majority of the European countries have specific
Biofilm is impossible to eradicate, but its requirements for monitoring for bacteria in the water
development can still be controlled.
distribution system.
Bacteria in the BIOFILM BIOFILM Free-floating bacteria
99.5% 0.5% These regulations have a common premise (circulating
loops, hot water temperatures, etc.) but they also have
specific aspects that could provide inspiration for
other countries.
In the majority of European countries there is a legal
obligation to safeguard the bacteriological quality
of the water in the system by regular monitoring,

3: Biofilm maturation phase I sampling and analysis. However, the methods and
subsequent follow-up action differ.

THE FIGHT AGAINST In France, the search for Legionella is obligatory.
WATERBORNE BACTERIA The Directive of 1st February, 2010 identifies three
levels of monitoring and sampling protocols. Since 1
st
January, 2012, monitoring has been extended to all
Infection control must be the priority for healthcare buildings open to the public.
facilities, which shelter many germs such as viruses Germany has adopted the same threshold levels
and bacteria. as France, while the United Kingdom is stricter: it
There are two types of waterborne bacteria which are conducts additional testing at levels over 100 Colony
responsible for healthcare acquired infections Forming Units per litre (CFU/L) and initiates curative
4: Biofilm maturation phase II in hospitals: procedures above 1,000 CFU/L.
- bacteria in the system which develop when in contact
with water e.g. Legionella spp.
- bacteria at the point-of-use (water controls) Monitoring levels for Legionella spp.:
which develop when in contact with air/water e.g. Alert level < 100 CFU/L
Pseudomonas aeruginosa, Mycobacterium avium,
Mycobacterium xenopi, etc. Remedial action > 100 CFU/L
Since these two types of bacteria are very different, up to 1,000 CFU/L
bacteriological monitoring must be appropriate Unacceptable level > 1,000 CFU/L
for both types. CFU/L: Colony forming units/Litre

For severely immunocompromised high-risk patients
5: Cell dispersion
in hospitals the draw-off at the point-of-use should
always be free from Legionella spp. bacteria.
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