Preventing nosocomial waterborne infections by controlling
water and water systems.
Leif Percival Andersen
Head of Infection Control
Copenhagen University Hospital, Rigshospitalet
Denmark
Water supply
 External water supply:
 surface water
 ground water
 Internal water supply:
 taps,
 showers
 supply to equipment.
External water supply
 External water supply



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Public,
Private
Surface water, lakes, rivers etc.
Ground water, wells etc.
External water supply
 External water supply
 Intent to have a low microbial content.
 Differs considerable around the world.
 The quality of the internal water supply
is not better than the quality of the
external water supply.
External water supply
External water supply.
Surface water
External water supply.
Ground water.
External water supply.
Bottle water.
Internal water supply
 Internal water supply
 Tap water,
 Showers,
 Water for equipment


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dental units,
dialyze units
ice cube machines
Water coolers
etc.
Complexity of water supply.
Internal water supply
 Internal water supply have two phases:
 1) Liquid phase with planktonic bacteria.
 2) Semisolid phase with microbial biofilm.
Planktonic phase
 Planktonic phase is free-living bacteria that
does not adhere to surfaces.
 This is the total germ count and Legionella
germ count is measured routinely.
Semisolid phase: biofilm.
 Biofilm consist of planktonic
microorganisms that have adhered to
surfaces (pipes, taps, aerators etc.) and
produce a matrix of glycoproteins, that
protect the dormant forms of
microorganisms.
Biofilm formation.
What increases biofilm
formation.
 Microorganisms in external water
supply.
 Water flow.
 Construction of pipe system.
 Material of pipes.
 “Dead ends”
Water flow
 Low water flow increases biofilm
formation.
 Taps acts as ”dead ends” when they are
closed.
 In ”dead ends” both planktonic and
biofilm microorganisms are increased
considerable.
Construction of pipes.
 Valves, bows etc. increases the
turbulence in the water system.
 Turbulence increases the formation of
biofilm.
Material of pipes.
 Stainless steel and PVC causes the
lowest biofilm formation.
 Results with copper are variable.
 All other materials seem to increase the
biofilm formation.
Water systems.
Constructions and dead ends.
End-point for water.
 Construction of taps.
 Aerators on taps.
 Shower tubes.
 Shower heads.
 Attachment of machines and equipment.
Taps, aerators and showers.
Drains
 Drains have a high content of biofilm
and different bacteria both from water,
patients and staff including pathogenic
bacteria.
 These bacteria can be released when the
drain is washed down or used.
Examples of increased germ
count.
 Aerators on taps
 Even though P. aeruginosa is absent in water
samples, it can often be found in imprints of
aerators because of biofilm formation.
 Shower tubes
 Germ count in showers increases 1-4 log10 within
two days because of biofilm formation in shower
tubes.
Which microorganisms form
biofilm?
 Most commonly it is bacteria that form biofilm
in water systems, but parasites may be incooperated in the biofilm.
 Sequencing of biofilms has revealed more
than 100 different bacteria in the same
biofilm.
Which microorganisms form
biofilm?
 Most bacteria spp. are able to produce
biofilm.
 Not all bacteria are equally good in
formation of biofilm.
 Not all strains of the same bacteria
species are equal good in biofilm
formation.
Which water-borne microorganisms cause human infection?
 Water-borne bacteria that most often
causes human infection:

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Legionella spp. primary L. pneumophilae
Pseudomonas aeruginosa
Acinetobacter spp.
Stenotrophomonas maltophilia
Other water-borne microorganisms
that may cause human infection.
 Other species may occasionally cause
infection in immune compromised patients:

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Sphingomonas spp.
Brevibacterium spp.
Methylobacterium spp.
Xanthamonas spp.
Water sampling
 Is traditional water sampling reliable or should
germs in biofilm also be measured?
 More than 90% of bacteria in water are viable,
but non-culturable.
 Germ count in biofilm need molecular
techniques such as sequencing.
Water sampling
 Most human-pathogenic bacteria are culturable,
but does the number corresponds with the
amount that may be released from biofilm?
 In our experience we do not see infections in
patients when total germ count is less than
5,000 germ/L and Legionella germ count is less
than 1,000 germ/L.
How to prevent water-borne
infections (systems).
 Never use water supply from old
buildings.
 There are several descriptions of water supply
to new hospital buildings that are connected to
water systems in old buildings with high germ
count.
 Both cold and hot water supply should be taken
from its own well or main water supply.
How to prevent water-borne
infections (systems).
 Keep a high water flow.
 Both construction and frequent use of
water systems are important.
 A high water flow will reduce the
thickness of the biofilm and thereby
reduce liberation of planktonic bacteria.
How to prevent water-borne
infections (systems).
 Avoid ”dead” ends including showers
and sinks that are not or rarely used.
 Pipes without water flow, sinks/taps and
showers that are never used will contain still
water where bacteria will propagate and cause
retrograde contamination of the water system.
How to prevent water-borne
infections (systems).
 Minimize side lines, connections and valves in
the pipe line system.
 Side lines, connection valves etc. will cause
turbulence in the water system which increases
the formation of biofilm.
 Strait pipes will have a linear water flow and
little biofilm formation.
How to prevent water-borne
infections (end point).
 Construction of taps should be simple.
 Recently nosocomial infections with
Pseudomonas aeruginosa have been
described in relation to electronic
forceps.
 Complex constructed taps may increase
biofilm formation. Mixed hot and cold
water is in the taps.
How to prevent water-borne
infections (end point).
 Aerators should have a program where
they are cleaned regularly.
 Aerators have large surfaces and where there
are still water all time when taps not are in use
and large biofilm formation occur especially
with P. aeruginosa.
 Regular cleaning of aerators are very important.
Water for equipment and
apparatuses.
 Dialyse machines
 Osmotic water supply with low germ count and
low endotoxins.
 Heat disinfection daily
 Dental units
 Several long thin tubes to the instruments
 Regularly heat or chemical disinfection can be
adapted
Water for equipment and
apparatuses.
 Water coolers
 Several different models – some with built-in
disinfection (filter, UV-light).
 Regular cleaning outside and inside
 Ice cube machines
 Several different models
 Regular cleaning outside and inside
How to prevent water-borne
infections (end point).
 Sterile filter on taps and in showers.
 Sterile filter on the tap or showerheads
with sterile filter prevent infections with
water-borne bacteria.
 At Rigshospitalet it is used when
nosocomial infections with water-borne
bacteria are seen in a ward or if the germ
count is repeatedly high.
Nosocomial Legionella
infections at Rigshospitalet.
Nosocomial Legionella Infections
5
Number
4
3
2
1
0
Nosocomial
Legionella Infections
Nosocomial P. aeruginosa
septicemia at Rigshospitalet.
Pseudomonas aeruginosa bacterimia/ septicimia
Incidensproportion 2005-2012
Total og nosocomial
1.00%
0.80%
0.60%
0.40%
0.20%
0.00%
2005
2006
2007
P. aeruginosa total
2008
2009
2010
2011
P. aeruginosa nosokomiel
2012
Nosocomial P. aeruginosa,
Acinetobacter spp and S.
maltophilia septicemia.
Conclusion
 It is possible to reduce nosocomial
infections caused by water-borne
bacteria, but it needs a great
complex of interventions.
A wet thank you.
Questions?