Rapid and simple DNA extraction method for the detection of enterotoxigenic Staphylococcus aureus directly from food samples: comparison of PCR and LAMP methods

The study describes the development of simple and rapid DNA extraction method in combination with loop-mediated isothermal amplification (LAMP) to detect enterotoxigenic Staphylococcus aureus in food samples. In this study, isolation of genomic DNA of enterotoxigenic Staph. aureus from spiked milk, milk burfi, khoa, sugarcane juice and boiled rice was carried out by boiling the isolated sample pellets for 10 min with 1% Triton X-100. The isolated DNA was evaluated by polymerase chain reaction (PCR) and LAMP method. The LAMP was found to be 100 times more sensitive than PCR. The LAMP assay was very specific for Staph. aureus, and the presence of other contaminating bacterial DNAs and food matrix did not interfere or inhibit the LAMP assay. The template DNA extraction method developed in this study for food samples is simple, rapid and cost-effective. LAMP was found to be less sensitive to matrix effect of food, compared to PCR. The method is suitable for direct detection of Staph. aureus without any enrichment in contaminated food samples and hence finds its application in food safety analysis, in permutation with LAMP.