Where the above is not feasible, cannot be guaranteed
or is not resource efficient, single use disposable
nebulisers should be used. All relevant personnel
should clearly understand the symbol indicating single
use (see symbol in Appendix I).87 Single use nebulisers
are not suitable for re-use. All relevant personnel
should clearly understand the consequences both in
terms of patient safety and personal professional
responsibility of poor practice in this area. Each
care setting's infection control manual should incorporate
details on the appropriate use and care of nebulisers.
For general practices, single use nebulisers are
recommended.
Ideally, the practice for patients living in their
own homes should be as above i.e. single patient use
and rinsing with sterile water following cleaning.
However, if this is not feasible, cooled boiled water
should be used.
(b) Water distribution system
Meet design requirements such as those outlined in
the UK HSC document, Legionnaires disease; the control
of Legionella bacteria in water systems. Approved
code of practice and guidance. Refer also to Section
4.13 in the risk assessment chapter - reducing Legionella
risks in new and refurbished buildings
All hospitals should be obliged to carry out a formal
risk assessment of the control and prevention of Legionella
bacteria.
The following summaries are based on HSE South Eastern
area's policies and procedures for the control of
Legionella bacteria in water systems in healthcare
settings and outline the actions that should be taken
by those principally concerned.
Manager of the facility
The manager of the facility/institution is responsible
for the appointment of a nominated/responsible person
and the provision of adequate support/resources to
enable them to carry out their duties In the event
of a case of Legionnaires disease the manager is
responsible for the provision of details of the risk
assessment for Legionnaires disease and hospital
procedure for the control and prevention of Legionnaires
disease to the investigation control team
Managers of acute hospitals should chair their local
Environmental Monitoring Committee (EMC).
Environmental Monitoring Committee
The subcommittee recommends that an EMC should be
established in each Health Service Executive area
to cover all long-stay institutions e.g. mental health
and physical disability facilities. They should also
be established in all acute hospitals
The EMC is responsible to the general manager for
advising on, and developing policies and procedures
for the control of Legionella in the healthcare premises
The EMC should monitor the formulation of the plans
for the implementation of these policies and procedures
and make recommendations as appropriate
The EMC should, in conjunction with managers throughout
the healthcare premises, ensure that all relevant
staff fully appreciate the actual and potential risks
of Legionella
The EMC should regularly review (not less frequently
than 12 monthly) the healthcare premises' performance
for Legionella control against its plans and present
a report on the review to the general manager.
Technical services officer or equivalent
The technical services officer or equivalent should:
Ensure that new systems are designed to the correct
standards such as those outlined in the UK HSC document,
Legionnaires disease; the control of legionella bacteria
in water systems. Approved code of practice and guidance.52
He/she should consult with clinicians and microbiologists
on special design for protection of high risk patients
e.g. ensuring the siting of air intakes are away from
cooling towers
Provide an expert back-up service to maintenance
and other operational departments, as required
Carry out specific projects as assigned, e.g. re-design
of systems
Provide technical advice to line management and other
departments at the various levels.
Maintenance/engineering personnel or equivalent
The responsible person appointed must conduct periodic
environmental monitoring where indicated (water sampling
and temperature recording), notify any unacceptable
results and arrange for appropriate remedial action
(this will include dental unit water supplies)
The responsible person appointed should carry out
a risk assessment of the water system(s)
He/she should ensure that routine inspections, maintenance
and disinfections are carried out as scheduled and
specified
He/she should ensure that water system modifications
and works are carried out in accordance with policy,
safely and to specification
He/she should ensure that all water system records
are created, maintained, kept up-to-date and displayed
at the appropriate locations.
Director of Public Health/Consultant in Public Health
Medicine
The director of public health (DPH)/consultant in
public health medicine (CPHM) should:
Advise managers in writing annually of at-risk locations
for nosocomial Legionnaires disease (see Chapter
1, Section 1.3) and the need to carry out sampling
for Legionella spp, using appropriate literature as
guidance (see Chapter 5 on sampling)
Arrange appropriate epidemiological investigation
of a case or outbreak of Legionnaires disease. This
should be done in liaison with the clinical microbiologist
where one is employed.
Establish and chair an incident control team in healthcare
settings where no microbiologist is employed
Inform HPSC
Inform the HSA if appropriate
Ensure relevant general practitioners (GPs) in the
area are informed where appropriate.
Microbiologist
The microbiologist should:
Provide advice on sources and ecology of Legionella
and on measures likely to prevent or eradicate colonisation
of hospital water systems
Educate physicians to heighten their suspicion of
Legionnaires disease and ensure appropriate diagnostic
tests are used for patients with pneumonia
Advise on the microbiological confirmation of any
case of Legionnaires disease
Alert other hospital consultants when there is a
confirmed case of nosocomial Legionnaires disease
Establish and chair an incident control team
Arrange laboratory testing of clinical and environmental
samples.
Infection control clinical nurse specialist
The infection control clinical nurse specialist should:
Formulate infection control policies as considered
necessary by the EMC and provide staff education on
these policies
Provide advice on infection control where appropriate,
to staff formulating other Legionella control policies
Educate personnel on the infection control aspects
of such policies.
Senior medical officer in department of public health
The senior medical officer (SMO) should:
Confirm any report of Legionnaires disease
Investigate the case, liaising with other members
of the investigating team to identify potential sources
of infection
The SMO should complete the HPSC enhanced surveillance
form (Appendix J) and collect any additional relevant
information using Checklist 5 and 6 in Chapter 8,
Section 8.2 by interviewing the patient or surrogate
Identify any additional risk groups by using the
enhanced surveillance form and checklist.
Principal environmental health officer
The principal environmental health officer (PEHO)
should:
Liaise with the SMO and public health department
re potential sources of infection identified on investigation
of the case
Coordinate the examination of potential environmental
sources of infection. This includes decision-making
re samples/environmental checks to be carried out
and assessment of buildings, operational difficulties,
etc. and where appropriate, the carrying out of such
testing by the environmental health service
In situations where the above expertise already exists
(e.g. in the acute hospital setting) the PEHO should
be kept fully briefed and advise on the appropriateness
of actions taken.
Hospital clinician
The hospital clinician should:
Assist at design stage of a new hospital unit or
modification by defining where high-risk clinical
activities take place e.g. transplant units, intensive
care units
Consider the diagnosis of Legionnaires disease in
all cases of pneumonia and to request Legionella diagnostic
tests if appropriate
For a possible nosocomial case of Legionnaires disease,
ensure that the patient or surrogate is interviewed,
the HPSC enhanced surveillance form is completed and
additional information is collected using the Checklist
5 and 6 in Chapter 8, Section 8.2.
Principal dental surgeon
The principal dental surgeon should:
Ensure that all currently available infection control
measures are put in place to minimise the contamination
of dental unit water lines and to advocate for further
design improvements.
Environmental services officer or equivalent
There should be an environmental services officer
or equivalent in all HSE areas and they should:
Provide a central leadership role in the management
of all environmental issues
Provide advice to the EMCs on how other areas are
achieving desired results
Audit and report on compliance with guidelines and
standards.
7.2 Legionnaires disease and holiday accommodation
It is important to realise that the source of a persons
illness could be one of many places and not just the
accommodation site itself. During any holiday, particularly
in warmer climates people will come into regular contact
with showers and air conditioning systems at multiple
sites. However, if two or more cases are linked to
the same site then it becomes more likely that this
is the source of their infections. At this point samples
of water may be taken from the site. If Legionella
are found in the water samples, and if appropriate
samples are available from the cases these can be
compared to see if they are the same. Microbiological
tests can be carried out which can prove that the
site was the source of a patient's infection. However,
this is not possible in most cases.
This disease is of particular relevance for travellers
since the clients at a hotel may come from many different
countries. The length of the incubation period means
that many people who are infected while travelling
will not become ill until after they return home.
This can make it hard for the authorities in one country
to locate the source of each cases infection. By pooling
the data for a number of countries it is possible
to identify accommodation sites that have been associated
with more than one case. The authorities of the country
in which the suspect site is located can then be informed.
The European Surveillance Scheme for Travel Associated
Legionnaires' Disease (EWGLINET) is one of the components
of the European Working Group for Legionella Infections
(EWGLI). EWGLINET operates as a disease-specific network
according to Decisions 2119/98/EC89 and 2000/96/EC90
for the setting up of a network for the epidemiological
surveillance and control of communicable diseases
in the Community. As of January 2008, 35 countries
(24 European Union (EU) member states and 11 non-EU
countries) were contributing or receiving data on
travel-associated cases.91 Liaison with other international
authorities takes place if the travel-associated infection
is linked to countries outside Europe, e.g. the USA,
Australia, Canada, the Caribbean and the Dominican
Republic.
Through the European Commission Directive for Package
Travel (90/314)(16) in 199692 tour operators in Europe
have a legal duty to protect the health and welfare
of clients within the package they deliver. Procedures
for reporting cases of travel-associated Legionnaires
disease to tour operators were formalised and adopted
by some European countries following the implementation
of the directive. These procedures were updated in
the review of the EWGLI guidelines which came into
use on January 2005. As a consequence, tour operators
are no longer routinely informed about clusters of
cases associated with tourist accommodation. However,
the EWGLINET coordinating centre in London informs
the International Federation of Tour Operators of
large outbreaks or clusters of three or more cases.
If a cluster involves three or more cases within a
short period of time and one or more cases were in
an Irish resident, HPSC as the EWGLINET collaborator
in Ireland, would inform the Irish Federation of Tour
Operators directly.
7.2.2 Reducing the risk of Legionnaires disease
in hotels and other accommodation sites
The risk of Legionnaires disease can be avoided.
Any organisation or premises (work-related or leisure-related)
which does not have an active programme to control
the growth of legionellae is negligent in ensuring
the safety of its workers, visitors, guests and others.
The programme should comprise the following:
Have one person responsible for Legionella control
Ensure that the named person is trained in the control
of Legionella and other staff are trained to be aware
of the importance of their role in controlling Legionella
Keep hot water circulating at all times at 50oC-60oC*
(too hot to put hands into or under for more than
a few seconds)
Keep cold water cold at all times. It should be maintained
at temperatures below 20oC
Run all taps and showers in rooms for several minutes
at least once a week whether room are occupied or
unoccupied
Clean and disinfect cooling towers and associated
pipes used in air conditioning systems regularly -
at least twice a year
Clean and disinfect water heaters (calorifiers) once
a year
Disinfect the hot water system with high level (50mg/l)
chlorine for 2-4 hours after work on water heaters
and before the beginning of a season
Clean and disinfect all water filters regularly -
every one to three months
Inspect water storage tanks, cooling towers and visible
pipe work monthly. Ensure that all coverings are intact
and firmly in place.
Inspect the outside of the cold water tanks at least
once a year and disinfect with 50mg/l chlorine and
clean if containing a deposit or otherwise dirty
Ensure that the system modifications or new installations
do not create pipework with intermittent or no water
flow
* Where these temperatures cannot be achieved due
to local conditions, suitable alternative residual
disinfection procedures must be used and supported
by regular (at least quarterly) testing for Legionella.
Residual disinfection procedures that have been used
include chlorine dioxide and copper/silver ionization.
If there is a spa pool, ensure that:
It is continuously treated with 2-3mg/l chlorine
or bromine and the levels are monitored each day before
the spa pool is used and thereafter at least every
two hours
Replace at least half of the water each day
Backwash sand filters daily
Clean and disinfect the whole system weekly
Keep daily records of all water treatment readings
such as temperature and chlorine concentrations and
ensure that the manager checks them regularly.
Further advice about specific controls should be
sought from experts in this field who can carry out
a full risk assessment of the hotel site
7.3 Dental chair unit waterlines
7.3.1 Introduction
Dental chair units (DCUs) are complex medical devices
designed to provide the equipment and services necessary
for the provision of a wide variety of dental procedures.
Water is needed to cool and irrigate a range of instruments
and tooth surfaces during dental procedures, as the
heat generated can be detrimental to teeth. Water
is also needed for oral rinsing during and following
dental treatment and to flush the cuspidor (spittoon)
bowl after the patient has finished rinsing. Dental
unit waterlines (DUWs) are an essential component
of modern DCUs and supply water as a coolant and irrigant
to turbine handpieces, ultrasonic scalers, three-way
air/water syringes, as well as supplying water for
the patient rinse cup filler and cuspidor.
Many studies have shown that output water from DUWs
is frequently contaminated with very high densities
of microorganisms, especially bacteria.93-95 This
is a universal problem and virtually all DUWs in standard
DCUs are likely to be contaminated.93-104 Figure 8
shows colonies of bacteria cultured from dental chair
unit output water. The different size and colours
of the colonies reflect the multi-species population
of microorganisms usually found in dental chair unit
waterline biofilm.
Bacterial contamination of DUWs is believed to originate
in the DCU water supply which usually contains low
levels of microorganisms. The main reason for the
extensive contamination present in DUWs is the complex
waterline network within DCUs. This network consists
of several metres of tubing with an internal diameter
of a few millimeters in which water can stagnate when
the equipment is not being used. Microorganisms in
water entering the DCU water supply (mainly aerobic
heterotrophic Gram-negative environmental bacteria),
attach to the internal surfaces of the waterlines
where they form microcolonies and eventually give
rise to multispecies biofilm. These biofilms are composed
mainly of bacterial exopolysaccharide, a slimy polysaccharide
material produced by bacteria that is highly hydrated
and contains both microcolonies and single cells,
interspersed heterogeneously with channels or pores.
Biofilm forms because the water at the edges of the
narrow-bore DUW tubing flows more slowly than water
at the centre of the tubing and thus there is little
or no disruption to the microorganisms present on
the inside surface of the waterline. Contact with
surfaces also causes the bacteria to become more adhesive.
This allows the microorganisms to attach and proliferate
whilst releasing some to continue on through the water
supply, as planktonic forms, where they may be deposited
at other sites within the tubing or are delivered
directly in to the mouths of patients during dental
procedures. Thus biofilm provides a reservoir for
ongoing contamination of dental unit output water.
Most of the bacterial populations found in DUWs also
occur in mains water, where they are present in lower
numbers. Biofilms often exhibit resistance to disinfectants
due to delayed penetration into the polysaccharide
matrix.105;106 The presence of Gram-negative bacteria
in waterline biofilm can also result in the presence
of bacterial endotoxin in DUW output water.107;108
Endotoxin consists of lipopolysaccharide (LPS) released
from the cell walls of Gram-negative bacteria following
cell death. Bacterial endotoxin levels 1000 endotoxin
units/ml have been recorded in DUW output water. In
contrast, the permissible levels of endotoxin allowed
for sterile water for injection in the USA is 0.25
units/ml. Significant doses of endotoxin may cause
adverse effects in susceptible individuals. The findings
of recent studies suggest that temporal onset of asthma
may be associated with occupational exposure to contaminated
DUWs among dentists.
7.3.2 Risk to patients and dental healthcare personnel
The presence of high densities of microorganisms
in dental unit water is a potential risk of infection
for dental patients and staff and is incompatible
with good hygiene and cross-infection control and
prevention practices. Furthermore, studies have shown
that waterborne bacteria are aerosolised during dental
procedures and that dental personnel and patients
are exposed to these microorganisms and fragments
of biofilm. DUW contamination is of particular concern
in the treatment of immunocompromised and medically
compromised individuals. These groups of individuals
frequently seek routine care in the modern dental
surgery.
Some of the bacteria found in dental unit water are
known to cause disease in humans. Of particular concern
are Pseudomonas, Legionella and non-tuberculosis Mycobacterium
species. Pseudomonas species, especially P. aeruginosa,
are well-known opportunistic pathogens that can survive
on a limited supply of nutrients, and which often
exhibit resistance to antibiotics and disinfectants.
It is important to emphasise that only a few cases
of infectious disease transmission related to DUWs
and related biofilm have been reported in the literature.
However, there is considerable potential for infection
with bacterial pathogens such as P. aeruginosa, L.
pneumophila as well as other organisms. In 1987, Martin
reported that abscesses caused by strains of P. aeruginosa
in two immunocompromised patients were attributable
to exposure to contaminated dental unit water. Martin
also isolated P. aeruginosa from the oral cavities
of 78 healthy patients for 3-5 weeks following exposure
to dental unit water contaminated with P. aeruginosa
There is no evidence that any patient has ever caught
Legionnaires disease from a dental chair. Several
studies have reported the presence of Legionella in
DUWs.101;115 In 1995, Atlas et al., reported the death
of a Californian dentist resulting from legionnaires
disease possibly due to exposure to dental unit water.100
Occupational exposure to aerosols of waterborne bacteria,
generated by dental unit handpieces, can also lead
to colonisation of dental staff and a higher prevalence
of antibodies to Legionella. One study of a group
of dental staff with more than two years clinical
experience revealed that 23% were IgG antibody-positive
and 19% were IgM antibody-positive for L. pneumophila,
compared to IgG antibody-positive levels of 8% for
individuals who had no clinical experience. The possibility
still remains that DUW-associated infections have
gone unrecognised or unreported because of the failure
to associate exposure to DUW aerosols with the development
of specific infections.115 Sporadic infections not
requiring hospital admission are also less likely
to be investigated or notified. There are also the
recognised risk factors for Legionnaires disease to
be taken into account: including being of an older
age group (>50 years), male, cigarette smoker,
and having a chronic underlying disease with or without
an associated immunodeficiency.
In recent years, there has been increased media and
public concern about the lack of infection control
within the healthcare system in general. Currently
there are no microbial quality standards imposed for
dental unit output water within the EU. However, it
is not unreasonable to expect that the quality of
dental unit output water should approximate the potable
drinking water standards. The potable water (drinking
water quality) standards set for the EU, the USA and
Japan are 100 cfu/ml, 500 cfu/ml and 100 cfu/ml, respectively,
of aerobic heterotrophic bacteria.70;117;118 In 1995,
the American Dental Association (ADA) established
a goal for the year 2000 of 200 colony forming units
(cfu) per ml of aerobic heterotrophic bacteria for
dental unit output water.68 However, this has not
been achieved in practice. The current CDC guidelines
for infection control in dental healthcare settings
recommend that dental unit output water should contain
500 cfu/ml of aerobic heterotrophic bacteria.119 A
recent symposium entitled Microbiology of dental unit
water lines; setting standards for the future, that
was held as part of the Pan-European Federation/International
Association for Dental Research meeting held at Trinity
College, Dublin, during September 2006 debated setting
a standard for DUW output water quality.69 The symposium
was the first occasion that scientists and clinicians
from academia and dental practice came together in
Europe to discuss the universal problem of DUW biofilm
and practical solutions. The consensus from the symposium
was that in the absence of an EU standard for DUW
output water quality, every effort should be employed
to ensure that DUW output water quality in Europe
complies with the ADA standard of <200 cfu/ml.
7.3.3 Control of Legionella bacteria in dental chair
unit waterlines
Numerous suggestions for reducing the bacterial density
in dental unit output water have been proposed but
none have been universally accepted which are both
efficient at eliminating bioflim, as well as being
safe for patients. One widely used practice for reducing
the bacterial density in dental unit output water
involves flushing DUWs with water. Flushing DUWs at
the start of the clinical session to reduce the microbial
density in output water does not affect waterline
biofilm or reliably improve the quality of the output
water used during dental treatment.99 Using tap water,
distilled water or sterile water in a self-contained
bottle reservoir system will not eliminate bacterial
contamination in output water if waterline biofilms
are not effectively controlled. While flushing can
result in a reduction in microbial density by several
orders of magnitude, studies have reported that microbial
densities after flushing were still unacceptably high.
The most efficient means of maintaining good quality
DUW output water is regular disinfection of DUWs with
a disinfectant or biocide that removes biofilm from
the waterlines resulting in output water of potable
quality.94;95;120;121 Very few studies have actually
investigated the efficacy of disinfectants to achieve
these desired effects in DCUs. However, a number of
recent studies have demonstrated the efficacy of a
range of disinfectant products approved for DUW disinfection
that efficiently remove biofilm and reduce bacterial
density to potable water quality or better.94;95;120-122
However, biofilm regrowth can occur within a week
or so following disinfection and so DUWs should be
disinfected at least once weekly with an appropriate
disinfectant. Disinfectants that contain a coloured
dye are particularly useful as they permit the individual
undertaking waterline disinfection to ensure that
each waterline is filled with disinfectant by visual
observation of the elution of the dye from handpiece,
scaler, cupfiller and three-in-one syringe waterlines,
etc. Care should be taken to avoid exposure to aerosolised
waterline disinfectant.
A wide variety of commercial waterline cleaning products
and systems are available.94;95;114;120-124 Dental
practitioners should contact the manufacturer of their
specific DCU model for advice on products and procedures
for waterline disinfection. In DCUs supplied with
a bottle reservoir, approved biocides can be added
to the bottle, aspirated into the waterlines and left
for an appropriate time to disinfect. Following disinfection,
all of the waterlines should be thoroughly flushed
to eliminate biocide. In DCUs supplied with mains
water, dental practitioners should contact the DCU
manufacturer for advice on biocide delivery. Some
brands of DCU are supplied with an integrated waterline
cleaning system.94;95;120 When choosing a biocide,
users should ensure that the efficacy and safety of
biocides for dental unit waterline disinfection have
been determined independently and the results published
in international peer-review journals.124 Manufacturers
should be able to provide this information.
For patient comfort, some DCU models provide heated
water (approximately 20C) to dental handpieces, ultrasonic
scalers and air/water syringes - ideal conditions
for the proliferation of Legionella bacteria. It is
recommended that qualified maintenance personnel,
having consulted the DCU manufacturer, should decommission
the water heaters in such DCUs.
Dental healthcare personnel should be educated regarding
water quality, biofilm formation, water treatment
procedures and adherence to maintenance protocols.
Dental practitioners should seek advice from the manufacturer
of their dental unit or water delivery system to determine
the most appropriate method for maintaining acceptable
output water quality. In general, waterlines should
be disinfected at least once a week with an approved
biocide.
Microorganisms, blood and saliva from the oral cavity
can enter the dental unit waterline system during
patient treatment. Thus handpieces, ultrasonic scalers
and air/water syringes should be operated for a minimum
of 20 to 30 seconds after each patient to flush out
retracted material. Even for devices fitted with antiretraction
valves, flushing devices for a minimum of 20 to 30
seconds after each patient is appropriate. Care should
be taken not to inhale the aerosol generated.
Water may be supplied to DUWs from a number of sources.
These include connections to the public water supply
mains, water storage tanks and independent reservoirs
within the DCU. Disinfectant can be introduced into
DUWs from independent reservoir bottles, or from disinfectant
delivery devices connected to the DCU water supply.
In the case of DCUs connected to public water mains
supply, it is imperative that the connection is turned
off prior to DUW disinfection to prevent contamination
of mains water with disinfectant. After disinfection,
DUWs should be thoroughly flushed with clean water
before DCUs are used for patient treatments. The water
distribution systems in some DCU models are fitted
with an air gap that physically separates the water
within DUWs from the supply water, thus preventing
backflow of disinfectant or contaminated water into
the supply water network
Saliva, blood and oral microorganisms can be aspirated
into DUWs during patient treatments due to faulty
handpiece antiretraction valves.119;125-127 This is
more likely to be a problem in older DCU models, older
handpieces and poorly maintained handpieces, although
a recent Italian study of 54 DCUs, comprising 18 different
models by six different DCU manufacturers demonstrated
an antiretraction device failure rate of 74% (40/54
DCUs tested).
Dental handpieces that are connected to DUWs and
which are used in the oral cavity, such as turbines,
ultrasonic scalers and air/water syringes, should
be run for a minimum of 30 seconds after each patient
treatment to flush out patient material that may have
been retracted into DUWs during use of the handpiece
during patient treatment.
There is an onus on DCU manufacturers to consider
the problem of DUW biofilm contamination when designing
DCUs. In fact a variety of disinfection devices and
systems are currently available for DUW disinfection,
although detailed comparative studies have yet to
be undertaken.
Regular disinfection of DUWs with an approved treatment
regimen and biocide should also effectively control
the levels of Legionella in DUWs. There is no need
for additional disinfection protocols. Dental healthcare
personnel should be familiar with the HPSC guidance
for control of Legionella. Each practice should undertake
a formal Legionella risk assessment which should be
revisited and revised annually. All water systems
(water tanks etc.) should be maintained as outlined
in Chapter 4 and 7. In relation to the water distribution
system supplying the dental clinic, hot water should
be circulated at a temperature of at least 50C and
cold water should be circulated at <20C to minimise
growth of Legionella. All redundant or seldom used
sanitary ware (i.e. showers, wash hand basins, toilets)
should be removed along with their supply pipes to
prevent dead legs (areas where water can stagnate).
7.3.4 Portable ultrasonic scalers and mobile DCUs
Portable auxillary units used by dental hygienists,
such as independent ultrasonic scalers, also require
cooling water. The DUWs in these units should also
be subject to regular disinfection (at least once
a week) with an approved biocide. The unit manufacturer
should be consulted in relation to the type of biocide
to be used. The DUWs of portable DCUs, such as those
that may be used by defence forces medical units as
part of mobile field hospitals or by Civil Defence
units, should be subject to disinfection in the same
way as conventional DCUs. Portable DCUs should have
their DUWs drained when not in use or during storage.
Following storage or during periods of infrequent
use, DUWs should be disinfected prior to patient treatment.
7.3.5 Record keeping, equipment maintenance, quality
assurance and periodic review of procedures
All DCUs should be serviced at appropriate intervals
as recommended by the manufacturer. The efficacy of
waterline cleaning should be tested periodically (six
monthly) using validated procedures. This can be achieved
by determining the aerobic heterotrophic bacterial
count in DCU output water immediately following disinfection
on R2A agar following seven days incubation at room
temperature (approx. 20C).94;95;120 A variety of commercial
laboratories can provide this service.
Written or electronic records of weekly waterline
disinfection, equipment maintenance and periodic waterline
cleaning efficacy testing should be retained.
7.4 Decorative fountains, water features and planters
in hospitals, other healthcare institutions and commercial
buildings
Many modern buildings including hospitals and other
healthcare facilities feature decorative fountains
and planters in an effort to make patients and visitors
more relaxed with their surroundings. The wet or damp
surfaces of fountains and other water features or
moist planter soils and trays readily become coated
with a growing biofilm of microorganisms unless particularly
well managed. This can act as a reservoir for their
transmission and dispersion.128;129 Such features
or activities near them may generate aerosols and
thus pose a particular risk of infection by Legionella
bacteria following aerosol inhalation.
7.4.1 Hospitals and healthcare institutions
Hospitals and other healthcare institutions (e.g.
day clinics, nursing homes, homes for the care of
the elderly) should not contain decorative fountains
or other water features that generate aerosols, as
the risk of disease transmission to immunocompromised
and debilitated patients outweighs their benefit.
However, when they are present in hospitals and other
healthcare institutions, features that generate aerosols
should be well maintained and periodically cleaned
and disinfected with an effective biocide. All wetted
surfaces should be disinfected and descaled if necessary.
This position is supported by a guideline issued by
the CDC for Environmental Infection Control in Health-Care
Facilities.61 Fountain and water feature maintenance
should be integrated with the hospital/institution
infection prevention and control and facilities maintenance
programmes and should be tested periodically for the
presence of Legionella bacteria. Fountain and water
feature water recirculation systems and spray heads
should be especially well maintained. Submerged lighting
should be discouraged as this can contribute to heating
of the water and result in water temperatures conducive
to the growth and proliferation of Legionella bacteria.128
Maintenance of fountains and water features during
the summer months is particularly important as elevated
air and water temperatures will encourage the growth
and proliferation of microorganisms. Many hospitals
and other healthcare institutions in the Republic
of Ireland already have water features that generate,
or can generate, aerosols, mostly in public areas.
If these cannot be maintained to minimise the risk
of disease transmission as indicated above, they should
be removed.
7.4.2 Hotels, restaurants and other commercial buildings
Water features that generate, or can generate, aerosols
are also often present in public areas in hotels,
conference centres and in other commercial buildings
and institutions. All of the considerations outlined
in the preceding section apply to fountains and water
features in these types of buildings. If fountains
and water features in hotels, conference centres,
etc. cannot be adequately maintained to minimise the
risk of disease transmission as outlined in the preceding
section, they should be removed.
7.4.3 Planning and design of new hospital and healthcare
buildings
Decorative fountains and other water features should
be excluded from hospitals and other healthcare institutions,
at the design and planning stage.
Small decorative water features
In recent years, small decorative fountains and water
features for use in buildings open to the public or
for use in private homes have become very popular.
These have been readily available to purchase in garden
centres, DIY stores, etc. Recently, a small decorative
fountain was shown to be the source of an outbreak
of legionnaires disease in the USA. The authors believe
that this was the first time that a small fountain
with apparently limited aerosol-generating capability
has been implicated as the source of a legionnaires
disease outbreak. Investigations of future community
cases of legionnaires disease should consider exposures
to small indoor decorative fountains, such as those
that might be present in private homes, restaurants,
hotels, or other businesses, as potential sources
of Legionella. Small decorative fountains should not
be used in buildings open to the public unless they
are particularly well maintained. The public should
be discouraged from using small decorative fountains
and water features in the home unless adequate maintenance
and disinfection procedures are provided with the
manufacturers instructions. In general, small water
features should be drained and cleaned weekly and
should be subject to manual dosing once a day with
liquid chlorine to develop 3-5 ppm free chlorine (or
equivalent) for one hour (observing adequate safety
precautions).
7.4.4 Recommendations for maintenance of decorative
fountains and water features
This section on spa pools is based on and should be
read with particular reference to the following document:
Management of spa pools: controlling the risk of infection,
published by the UK Health and Safety Executive and
HPA, 2006. Available at http://www.hpa.org.uk/publications/2006/spa_pools/spa_pools.pdf.
A spa pool is a self-contained body of warm, agitated
water designed for sitting or lying in up to the neck
and not for swimming. It is not drained, cleaned or
refilled after each user but after a number of users
or a maximum period of time. It is filtered and chemically
disinfected.
Spa pools contain water heated to 30oC - 40oC and have
hydrotherapy jet circulation with or without air induction
bubbles. They can be sited indoors or outdoors. Common
terms for spa pools include hot spa, hot tub, whirlpool
spa and portable spa. Jacuzzi is the registered trade
name of a specific manufacturer and should not be mistaken
for a generic name for spa pools.
Commercial spa pools
A commercial spa pool is an overflow/level deck spa
pool installed in a commercial establishment or public
building and generally used by people visiting the premises.
Typical sites for commercial spa pools include hotels,
health clubs, beauty salons, gymnasia, sports centres
and clubs, swimming pool complexes and holiday camps.
A spa pool in such a location is considered commercial
even if payment for use is not required.
A domestic spa pool installed in a hotel bedroom or
holiday home should also be managed as a commercial
spa pool. Similarly spa pools rented out to domestic
dwellings for parties etc. must also be considered commercial.
A domestic spa pool or hot tub is a freeboard or overflow/level
deck spa pool installed at a private residence for the
use of the owner, family, and occasional invited guests.
These are typically used in beauty parlours, health
suites, hotels and dwellings. They are also being used
in healthcare premises. Water within the bath is untreated
and the bath is drained following each use. Whirlpool
baths experience similar problems to spa pools with
the formation of biofilm within the pipework system
associated with the air and water booster jets, so regular
disinfection is recommended. They are unsuitable for
use in healthcare facilities as the risks outweigh the
benefits.
The hazards associated with the use of natural spas
are essentially the same as with artificial spa pools.
Hydrotherapy pools are pools used for special medical
or medicinal purposes. Thalassotherapy pools use seawater
or sea products e.g. seaweed, for health or beauty benefits.
Many of the principles that apply to spa pools also
apply to these.
Spa pools are potentially a high-risk source of pathogenic
microorganisms, including Legionella. They should be
designed, installed, managed and maintained with control
of microbial growth in mind.3 Spa pools are much smaller
than swimming pools and have a higher ratio of bathers
to water volume so the amount of organic material in
spa pool water is far higher than in swimming pool water.
They also have an extensive surface area within the
pipes used to provide both the air and water-driven
turbulence.134 The pipes and balance tank are often
inaccessible and difficult to clean and drain and may
have areas of stagnation which allows biofilm to grow.
The pipes above the waterline often do not receive disinfection
from the pool water which also predisposes them to biofilm
formation.3
Infectious agents can easily be introduced to a spa
pool via bathers, from dirt entering the pool or from
the water source itself. Once in the spa pool, conditions
often exist which promote the growth and proliferation
of these agents.134 Legionella bacteria frequently grow
in poorly designed and poorly managed spa pools.
The water is vigorously agitated and this leads to
the formation of aerosols that can be inhaled. This
means even people not in the immediate vicinity of the
spa pool can breathe in the aerosol.3 There have been
a number of outbreaks of Legionnaires disease associated
with spa pools in recent years.11;135 Spa pools are
the commonest source of Legionnaires disease outbreaks
on cruise ships (see section on cruise ships). Water
disinfection is therefore a key control measure in spa
pools although the raised temperature and high organic
content can make it difficult to maintain effective
disinfection.
7.5.3 Duties of designers, manufacturers, importers
and suppliers
Under section 16 of the Safety, Health and Welfare
at Work Act 2005,136 a person who designs, manufactures,
imports or supplies a spa pool, must ensure, as far
as is reasonably practicable, that the pool is designed
and constructed so as to be safe and without risk to
health when properly used by a person at work. They
must ensure that adequate information is provided to
ensure its safe use including information on its safe
installation, maintenance, cleaning, dismantling or
disposal. Any revisions of the information must also
be provided if a serious risk to health or safety becomes
known.
Consideration should be given to the materials used
during design and installation, avoiding materials that
support microbial growth. All parts of the system should
be accessible to facilitate easy cleaning, disinfection
and maintenance. Spa pools should not be located too
near swimming pools.
7.5.4 Identification and assessment of the risk associated
with spa pools
It is the responsibility of the person operating a
spa pool (duty holder) to ensure that persons in or
around the spa pool are not exposed to infectious agents
including Legionella (not applicable to spa pools used
for domestic purposes). In order to do this a written
risk assessment must be undertaken. When conducting
a risk assessment of a spa pool, the individual nature
of the premises and spa pool should be considered. In
this regard, it is important to have an up-to-date schematic
diagram of the spa pool and associated plant. This can
be used to decide which parts of the spa pool pose a
risk to workers and users
The person conducting the risk assessment should have
adequate knowledge, training and expertise to understand
and control the risk associated with Legionella in spa
pools. They should also have the authority to collect
all the information needed to do the assessment and
to make the right decisions about the risk and precautions
or control measures needed.
7.5.5 General factors to be considered in the risk
assessment
General factors to be considered in the risk assessment
include:
The significant findings of the risk assessment should
be recorded. The written risk assessment should be linked
to other health and safety records e.g.
The risk assessment should be reviewed at least annually
and whenever there is a reason to suspect that it is
no longer valid e.g.
Everyone involved in the risk assessment and management
of spa pools should be competent, trained and aware
of their responsibilities. The control measures and
their implementation should be regularly monitored.
Staff responsibilities and lines of communication need
to be clearly defined and documented.
The results of any monitoring, inspection, test or
check carried out on the spa pool, along with dates.
The records must be available for inspection by the
HSA and should be available for inspection by environmental
health officers. The results of monitoring, inspections,
testing or checks should be kept for at least five years.
It is the responsibility of the owner to arrange routine
microbiological or chemical testing. Poolside testing
and recording of residual disinfectant and pH levels
should be undertaken before the spa pool is used each
day and thereafter at least every two hours in commercial
spa pools. The following on-site indicators should be
monitored:
7.5.10 Summary of spa pool checks (excluding domestic
pools)
Source: HSE and HPA Management of spa pools: controlling
the risks of infection (summary of checks, Section 2.3.8)
Travelling aboard ship or being aboard ship is an established
risk factor for legionellosis. There have been numerous
cases of legionellosis acquired on ships and thus appropriate
management of wet environments on ships is vital to
prevent such outbreaks.137-143 Essential control measures,
such as proper disinfection, filtration and storage
of source water, avoidance of dead legs and regular
cleaning and disinfection of spa pools are required
to minimise the risk of legionellosis on ships. The
World Health Organization (WHO) currently provides comprehensive
guidance on Legionella risk assessment and control measures
in relation to ships in its document Guide to Ship Sanitation.
This document should be consulted for detailed guidance
relating to the management of Legionella risks aboard
ships.
Ships are considered to be high-risk environments for
the proliferation of Legionella bacteria for a variety
of reasons:
Ships should be supplied with potable water. However,
even if there are low numbers of Legionella bacteria
in the water taken aboard ship, Legionella bacteria
can still proliferate due to factors within the ship
environment, including periods of water stagnation and
elevated water temperatures. The occurrence of high
densities of Legionella bacteria in drinking water aboard
ship is avoidable through the implementation of basic
water quality management procedures:
It is imperative that all pipework and storage tanks
are insulated appropriately to ensure that hot and cold
water are provided within the temperature ranges mentioned
above.
High water temperature is the most efficient approach
for continuous control in a hot water system. However,
it is important to note that maintaining operating temperatures
of hot water systems above 50C may present a scalding
risk at outlets. Maintaining cold water temperatures
at < 20C is very effective in preventing the proliferation
of Legionella bacteria but may be difficult to achieve
in some water distribution systems, particularly during
warm weather. In the case of the latter, maintaining
a residual disinfectant in the cold water distribution
system (e.g. > 0.5 mg/litre free chlorine) is essential.
It is essential that the water distribution systems
aboard ships are designed and maintained to minimise
opportunities for proliferation of Legionella bacteria.
Pumps, backflow prevention devices and thermostatic
mixing valves should be installed correctly and maintained
regularly by appropriately trained personnel. In relation
to maintenance, the following points need be considered:
Frequent monitoring of control measures is required
to ensure that the system is operating within limits
and to provide early warning of deviations. Monitoring
should include:
Microbial testing.
Legionella can proliferate aboard ship in poorly maintained
spa pools and whirlpools, and associated equipment.
Specific risk factors include frequency of spa pool
use and length of time spent in or around spa pools.
Legionella levels can be kept under control through
the implementation of appropriate controls, including
filtration and maintenance of a continuous residual
disinfectant biocide in spa pools, and the physical
cleaning of all spa pool equipment including associated
pipework and air conditioning units [see Section 7.5]
Water used in decorative fountains and water sprays
in HVAC* air-distribution systems should originate in
the ships potable water system and should be treated
with biocide to avoid microbial build-up in the operation
of the sprays and fountains. Decorative fountains and
water sprays in HVAC air-distribution systems should
be maintained free of algae and moulds [see Section
7.4]
Showerheads should be cleaned and maintained regularly
[see Chapter 4, Section 4.15.2] *HVAC is an acronym
for heating, ventilating and air conditioning
