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ALS & LCA - Raising awareness of increasing legionella positivity rates post lockdown

Jan 27, 2022

ALS are proud to be members of the Legionella Control Association and as members we provide a range of products and services for the control of legionella bacteria in water systems whilst demonstrating that we have complied with the LCA Code of Conduct and LCA Service Standards and are committed to helping their customers prevent legionellosis and keep their water systems safe.

Recently The Legionella Control Association in conjunction with HSE, PHE and Local Authorities held a webinar aimed at raising awareness of increasing legionella positivity rates post lockdown. The data demonstrated that the average positive rate in the UK had increased by around 2% following the lockdowns in response to COVID-19.

Post the webinar, questions were asked if there were particular species that could have led to an increase and with this in mind, LCA approached ALS and other Labs and asked us to share our results data. Further details about the study can be found here:

This study is in its infancy and further research needs to take place before any significant changes are considered or undertaken. However, it is clear to see from this data that the prominence of species of legionella, other than pneumophilia, should be considered when undertaking a sampling and analytical plan.

Our Legionella laboratory based in Coventry participates in a wide range of Proficiency Testing schemes offering two categories of Legionella testing. Both methods are highlighted in the Approved Code of Practice for Legionella (ACoP L8), HSG 274 and HSG 282.

The ALS methods are:

  1. Detection by Standard Culture, based on ISO 11731:1998, utilising our MALDI-ToF instant confirmation.
  2. Enumeration of Legionella by Rapid Detection using a method based on the Polymerase Chain Reaction (PCR).

​Maldi-ToF instant confirmation is the rapid identification of positive Legionella and Microbiological samples by Matrix Assisted Laser Desorption and Ionisation by Time of Flight (MALDI-ToF) Mass Spectrometry. The ground breaking identification technique first employed by ALS Environmental into the Environmental Testing market, known as MALDI-ToF technology, allows us to remove the need for presumptive data for Legionella and all other bacteriological analysis, with all data reported as Colony Forming Units (CFU).

The method utilised by ALS allows us to identify both Legionella Pneumophila and Legionella Species and we can analyse 96 isolates in a single batch. If a Species is identified using the MALDI-ToF method then ALS are able to identify over 98% of samples to both genus and species level, for which we maintain one of the largest libraries of Legionella Species in the world.

The ALS Environmental PCR method can detect Legionella that live and thrive in Amoebae and Biofilms that the traditional method cannot detect due to the limitations of the culture method, these are known as "viable but none culturable bacteria" (VBNC). Stress factors such as Temperature, Anti-biotics and competing bacteria on the agar can induce a VBNC state.

If you would like further information on Legionella testing please do not hesitate to contact the Client Services team at Coventry who will be happy to assist with your enquiry

Phone - 02476 42 12 13
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