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 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