Legionella

Accreditation: The culture method is UKAS accredited for potable, process, swimming pool and hospital waters.  Our FASTek method is not currently accredited by UKAS.

Sample volume: The standard sample volume is 1 litre although the analysis can be performed on any volume. The certificate of analysis will reflect the volume tested.

Turnaround time: 10 -14 days for the culture test and 24 hours for FASTek samples

Expression of results: cfu/litre or cfu/volume tested (culture method).  Detected or Not Detected (FASTek).

 

We have one UKAS accredited method for the analysis of Legionella which is the traditional ten day culture test, and a second non-accredited rapid method known as FASTek. The FASTek method detects Legionella pneumophila serogroups 1-15 but not non-pneumophila species of Legionella.

The FASTek method will very quickly screen out samples that are negative for Legionella allowing the results to be reported within 24 hours, and if urgently required, within approximately six hours of receiving the sample. FASTek samples are always tested by culture in addition to the rapid screen – this is to provide confirmation and enumeration of positive samples and also to check for the presence of non-pneumophila species.  It is not uncommon for FASTek positive samples to be reported as culture negative as this method detects viable non-culturable bacteria as well as having a low limit of detection.

For both methods we prefer to receive a 1 litre sample as per the British standard method. We are able to test other volumes of water, however the sensitivity of the method reduces as the sample volume decreases.

Results will typically be emailed as PDF reports but we can send results in your preferred format. We will also notify you immediately if any positive results are detected and identified so you don’t have to wait for ten days before being able to take action.

Currently there are at least 46 species of Legionella, most are of little significance to public health. The most significant species is L.pneumophila with regards to causing human infection.

L.pneumophila has at least 35 serogroups, with serogroup 1 being the one most commonly associated with infection. Typically laboratories will test for the first 14 serogroups but will report serogroup 1 individually and group together serogroups 2 – 14. The remaining serogroups are not specifically identified as routine methods do not allow this.

When a water sample is tested the analysis will determine if L.pneumophila is present and then determine if the isolate is serogroup 1, if it belongs to serogroups 2 – 14, or if it is one of the other Legionella species for example L.longbeachae 1 & 2, L.bozemanii 1 & 2, L.dumoffii, L.gormanii, L.jordanis, L.micdadei and L.anisa .

The way the analysis is performed does not allow the identification of the exact species. With respect to water treatment if these species are present it indicates that the system is capable of supporting the growth of L.pneumophila. If these species are present in high numbers in the presence of a vulnerable population the infection risk can still be significant.

In terms of Legionella compliance the presence of any species of Legionella indicates that the system may be out of control.

 

This laboratory will report results as:

L.pneumophila serogroup 1, cfu/litre

L.pneumophila serogroups 2-14, cfu/litre

Legionella species (NOT pneumophila), cfu/litre