50
Complex water systems, such as those for heating water, refrigeration
in air conditioning, swimming pools, and whirlpool baths use water in
a temperature range that allows or encourage the growth of Legionella,
besides, these systems can produce aerosols thus increasing the propagation
of the bacterium and the risk of contagion and onset of the Legionnaires’
Disease.(Bartram
et al
., 2007)
The Legionellae were already isolated in many natural environments,
rivers, frozen lakes, hot springs in the vicinities of volcanos, showing that
they can survive naturally and that they reproduce in temperatures between
25 and 45 °C, having an optimal growth temperature that ranges between
32 and 42 °C.
The L. pneumophila is resistant to temperatures of up to 50 °C for several
hours. Temperature is a crucial factor in the proliferation of
Legionella
ssp
, being so, the temperature of the water in an artificial system must be
considered as an important risk factor in controlling Legionella.
Effects of other microorganisms in the growth of
Legionella ssp
.
Nutrient requirement.
Sterile water is not sufficient for the multiplication of
Legionella ssp
. In
studies made with sterile distilled water, the bacterium survived for long
period, but not enough to multiply. Whereas in tap water (not sterile),
the multiplication occurs naturally. These studies suggest that
Legionella
ssp
requires nutrients that can be provided either directly or indirectly by
other associated microorganisms, under the form of dissolved organic
compounds, through the excess of production of organic compounds or
