Evaluation of an immunochromatographic assay for rapid detection of Salmonella enterica serovars Typhimurium and Enteritidis

An immunochromatographic assay was developed to detect Salmonella enterica serovars Typhimurium and Enteritidis in a single strip. The assay was constructed in the form of a sandwich, using 2 specific anti-S. Typhimurium and anti-S. Enteritidis antibodies immobilized on a nitrocellulose membrane at separated test lines, while the other specific antibody to Salmonella spp. was conjugated with gold nanoparticles. The test strips can immediately detect S. Typhimurium and S. Enteritidis specifically in a culture medium at levels as low as 10(4) and 10(6) cfu/ml, respectively. The contamination of S. Typhimurium and S. Enteritidis at 1 cfu/ml or greater can be detected by the test strips after 6-24 hr incubation. The specificities of the test strips to detect S. Typhimurium and S. Enteritidis, in spiked samples, were obtained at 100%; the sensitivities were at 98.89% (89/90) and 87.50% (70/80), respectively, compared with the conventional method. The newly developed multiplex immunochromatographic assay is the first report on the efficient detection of both S. Typhimurium and S. Enteritidis simultaneously in single strip. This test strip also provides advantages of simplicity and very rapid detection of these specific bacterial contaminants in chicken and can be useful for mass detection on chicken farms and in other veterinary products.