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Fluorescence immunoassay for detection of pathogens

Listeriosis is a foodborne infectious disease caused by the pathogen Listeria monocytogenes and is particularly serious for pregnant women and immunocompromised persons. The pathogen is spread mainly through spoiled and contaminated food or animal feed. Methods for the detection of Listeria monocytogenes (LM) on surfaces in the food industry have been developed to control the spread of the pathogen, but these are time-consuming and require special equipment. In the presented study, a fluorescence sandwich immunoassay was developed using a chitosan cellulose nanocrystal (CNC) membrane to detect Listeria monocytogenes on surfaces.

Tags: Biofilm, pathogens

A fluorescence immunoassay for a rapid detection of Listeria monocytogenes on working surfaces

Capo, A., D’Auria, S. & Lacroix, M. Sci Rep 10, 21729 (2020). doi.org/10.1038/s41598-020-77747-y

The p60 protein is found on the surface of the Listeria cell wall and is released into the extracellular environment. For the developed sandwich immunoassay, LM mAb antibodies were covalently immobilized on the CNC membrane. The p60 protein of the pathogen Listeria monocytogenes binds to this capture antibody when present. Detection of the bound p60 protein is then performed using the fluorescently labeled LM pAb antibody.

The developed assay was tested for sensitivity, specificity and required growth time of the pathogen. It was also investigated whether there is a cross-reaction with other pathogenic bacterial strains such as E.coli, S. Typhi or L.innocua. The authors used Chitosan 85/1000 (deacetylation degree/viscosity) from Heppe Medical Chitosan GmbH for the membrane.

Results

  • CMC membrane allows improved capture of p60 protein-specific antigen.
  • faster analysis time (12 instead of 24h)
  • detection limit of 102 CFU/ml (2log)
  • high specificity
  • no cross-reaction with five other common pathogenic bacterial strains

Conclusion: The developed platform with chitosan-cellulose nanocrystal membrane allows the detection of Listeria monocytogenes after only 8 hours at a starting concentration of 102 CFU/ml. The reliability of the technology is comparable to already used methods, but significantly faster.

Source: https://www.nature.com/articles/s41598-020-77747-y

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