Plumbing Connection Spring 2016

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SPRING 2016
diseases or misdiagnosis. This contributes to the much
higher mortality rate of 33% for hospital acquired
Legionnaires disease, compared to 13% for community
acquired cases of the disease2.
Closer to home, one of Australia’s biggest outbreaks
occurred in 2013, when contaminated warm water drawn
through hospital taps at Brisbane’s Wesley Hospital resulted
in the death of a patient and left another critically ill in
intensive care. It was reported that a State Government
energy efficiency program may have increased the risk of
Legionella bacteria growing in water supplies. Temperature
controls in place at the hospital meant water could not
reach a temperature higher than 45°C. This created an
optimum environment for bacteria growth.
LEGIONELLA AND HOSPITAL WATER SYSTEMS
During a recent study of 8 hospitals in the US and Spain,
100% of hospital water systems colonized with Legionella
reported hospital acquired Legionnaires disease, which was
uncovered following subsequent clinical surveillance3.
In a US National surveillance study of 20 hospitals, 14
were found to have water systems colonized with Legionella,
with 6 of the 14 reporting high levels of contamination. Of
the six hospitals, four discovered cases of hospital acquired
Legionnaires’ disease3.
Stagnation is another key breeding factor that will
exacerbate Legionella growth in water systems. When water
is used infrequently or where there are significant dead
legs in pipework, the risk of contamination is increased.
It is both good design practice and the requirement of
various State Health guidelines to reduce the length of
warm water pipework in order to minimise dead legs, and in
some circumstances to remove them completely as well as
ensuring systems are flushed on a weekly basis when taps
have not been in use.
LEGIONELLAE IN COLDWATER SYSTEMS
While warm water systems have historically been the
cause of many outbreaks of Legionella, due to their
LEGIONELLA
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WHENWATER IS USED INFREQUENTLY
OR WHERE THERE ARE SIGNIFICANT
DEAD LEGS IN PIPEWORK, THE RISK
OF CONTAMINATION IS INCREASED.