Rapid identification of Salmonella using Hektoen enteric agar and 16s ribosomal DNA probe-gold nanoparticle immunochromatography assay in clinical faecal specimens

A rapid identification of Salmonella, one of the most common foodborne pathogens worldwide, in clinical patients can enable better rational managements and prevent further outbreaks. The traditional immunochromatography using antibody–gold nanoparticles (Ab-AuNPs), such as the home pregnancy test, has been used for the Salmonella detection. In this study, we developed a new and rapid method using DNA probe-AuNPs for the detection of 16s ribosomal DNA of Salmonella. To evaluate the proposed method in clinical specimens, we performed a clinical test by identifying 159 stool samples on Hektoen agar containing black or crystalloid colonies using the method and the VITEK 2 system for confirmation. Eighty of the isolates were correctly identified as Salmonella to achieve 100% sensitivity. Seventy-five samples were correctly identified as non-Salmonella spp., but four were incorrectly identified as Salmonella. The specificity was 94·93%. The assay time is about 30 min after the DNA purification. The time-consuming and labour-intense biochemical tests can be replaced. We demonstrated that this assay is a rapid, convenient and cost-effective tool for Salmonella identification of clinical faecal samples, which is worth for further promotion and clinical use. This is the first application of using 16s ribosomal DNA probe-Au-NPs and immunochromatography on clinical samples. Significance and Impact of the Study This is the first application of using 16s ribosomal DNA probe–gold nanoparticles and immunochromatography method on clinical samples with sensitivity 100% and specificity 94·93%. The assay time is about 30 min after the DNA purification. We find this assay a rapid, convenient, sensitive and inexpensive tool for Salmonella identification of clinical faecal samples, which is worth further promotion and clinical use and can replace the traditional time-consuming and labour-intense biochemical tests. The potential benefit of this approach is to develop a rapid point-of-care test that provides results while the patient is still at the doctors' office.