197
in the sample it may occur the loss of viable
Legionella
during transportation
and with this, can lead to have a “false negative” result, providing some
“unreal” comfort and tranquility.
The effect of lysis of protozoamay occur at themoment of the processing
of the sample, because in the ISO 11731-2 method, the test is made by
filtration, as illustrated in Figure 01, where it is used a membrane filter
with microscopic pores and a vacuum pump for suction of the water. This
disturbs strongly the sample, which can cause the disruption of the amoebae
and ca release high concentration of
Legionella
in the water, thus causing
a false-positive result. In Figure 02 please see illustration of positive for
Legionella pneumophila
.
Figure 01
– Filtration procedure of the ISO 11731 02
technique.
Figure 02
– Presence of
Legionella pneumophila
bacteria isolated by the ISO 11731-2 method.
