Detection of Listeria monocytogenes using an immunochromatographic point of care test based on anti-internalin A and B antibodies and a nano-biotinylated detection complex

Abstract

The detection of Listeria monocytogenes, a Gram-positive food-borne bacterium, helps prevent listeriosis outbreaks, an invasive disease with high mortality rates among immunocompromised individuals. Microbiological culture methods are time-consuming, requiring laboratory infrastructure while molecular techniques are expensive and require complex equipments. We have developed a point of care test (POCT) based on lateral flow immunochromatography, combining anti-Internalin A and B antibodies and the biotin-streptavidin system into a nano-biotinylated detection complex. The new lateral flow prototype presented the following visual limit of detection (LOD):102 CFU/mL in pure cultures of L. monocytogenes; 102 CFU/mL or/25 g in samples of artificially contaminated milk, lettuce, mozzarella cheese, hamburger. Quantitative analysis indicated LOD between 102–10 CFU/mL in pure cultures of L. monocytogenes. The prototype showed 100% specificity when tested with pure cultures of Listeria innocua, Bacillus cereus, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Micrococcus luteus, Serratia marcescens, Enterobacter aerogenes, Enterococcus faecalis, Enterobacter cloacae Salmonella Enteritidis, Salmonella Typhimurium and Klebsiella pneumoniae. Unlike commercially available tests, this prototype showed detection capacity closer to the minimum L. monocytogenes infectious dose. Therefore, this prototype represents a promising POCT candidate allowing the quick, specific, and sensitive detection of L. monocytogenes in food matrices and on food production platforms.