Arrigo I, Serra N, Mariyam L, Sarvandani MM, Tricoli MR, et al. PLOS ONE 20(12): e0336207.
Highlights:
- 75 environmental water samples, collected in 2 separate bottles, were analysed in parallel using culture according to ISO 11731:1998 (concentration, membrane filtration and heat treatment in parallel with a direct inoculation of the concentrated treated sample (100 μL) and non-treated sample into GVPC agar), Legiolert, and real-time (rt) PCR for the detection of pneumophila.
- The data showed that Legiolert detected more positive samples from a 100 mL sample rather than the ISO standard 1000 mL with sensitivity, specificity and accuracy > 80%. One possible explanation for the higher recovery rate is that pneumophila may propagate better in a liquid medium than on a solid one.
- Legiolert offers several advantages over the conventional culture method, including ease of use, shorter time requirements, and fewer resources needed, however it doesn’t detect other Legionella species.
- rt PCR is a promising complementary tool to the standard culture-based approach for detecting pneumophila and could be particularly valuable during a Legionnaires’ disease outbreak due to its high sensitivity, rapid acquisition of results and the easier handling of large sample amounts, particularly for screening negative samples.
- A limitation is that the high levels of pneumophila detected by rtPCR could represent viable but non-culturable (VBNC) cells or DNA from lysed cells, so positive results should be carefully interpreted and may not always indicate an immediate health risk to vulnerable individuals.
