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

The detection of Listeria monocytogenes, a Gram-positive food-borne bacterium, helps prevent listeriosis out-breaks, 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 Salmo-nella 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.