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

Aims: 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.
Methods and Results: 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.
Conclusions: 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.
Significance and Impact of the Study: 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.