Rapid culture‐based detection of Legionella pneumophila using isothermal microcalorimetry with an improved evaluation method

Abstract

The detection and quantification of Legionella pneumophila (responsible for legionnaire's disease) in water samples can be achieved by various methods. However, the culture-based ISO 11731:2017, which is based on counts of colony-forming units per ml (CFUÁml -1 ) is still the gold standard for quantification of Legionella species (spp.). As a powerful alternative, we propose real-time monitoring of the growth of L. pneumophila using an isothermal microcalorimeter (IMC). Our results demonstrate that, depending on the initial concentration of L. pneumophila, detection times of 24-48 h can be reliably achieved. IMC may, therefore, be used as an early warning system for L. pneumophila contamination. By replacing only visual detection of growth by a thermal sensor, but otherwise maintaining the standardized protocol of the ISO 11731:2017, the new procedure could easily be incorporated into existing standards. The exact determination of the beginning of metabolic heat is often very difficult because at the beginning of the calorimetric signal the thermal stabilization and the metabolic heat development overlap. Here, we propose a new data evaluation based on the first derivation of the heat flow signal. The improved evaluation method can further reduce detection times and significantly increase the reliability of the IMC approach.

Selective Detection of Legionella pneumophila Serogroup 1 and 5 with a Digital Photocorrosion Biosensor Using Antimicrobial Peptide-Antibody Sandwich Strategy

“…Presently, culture-based methods are widely used and considered gold standard techniques for detecting pathogenic L. pneumophila [ 3 ]. However, these approaches are both labor intensive and time consuming [ 4 ], typically taking up to ~10 days to quantify growing bacterial colonies [ 5 ]. Other techniques, such as polymerase chain reaction (PCR) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) spectroscopy provide accurate and relatively fast detection [ 6 ].…”

Rapid Detection and Differentiation of Legionella pneumophila and Non-Legionella pneumophila Species by Using Recombinase Polymerase Amplification Combined With EuNPs-Based Lateral Flow Immunochromatography

“…Therefore, the rapid detection of Legionella is of great significance for the protection of human health. By using a thermal sensor instead of the visual detection of growth, the culture-based isothermal microcalorimetry (IMC) method could shorten the detection time to 24-48 h (Fricke et al, 2020). As the gold standard, the qPCR assay appears useful for applications in detection of Legionella bacteria (Kontchou and Nocker, 2018;Toplitsch et al, 2018).…”

Serotyping of Legionella Bacteria Isolated from Various Water Systems in the Central Anatolia Region

“…Legionella lives and proliferates by forming colonies in the biofilms of water systems (2)(3)(4). Thus, they represent a great danger to humans (5,6). Additionally, they can resist environmental conditions by forming an exopolysaccharide matrix or by entering a "viable but non-culturable" state.…”