Abstract:
Staphylococcus aureus is an important pathogen of humans. It is also the most common cause of foodborne illness. Staphylococcal food-borne disease is a typical intoxication due to enterotoxins ingestion performed in food by enterotoxigenic strains. Here we developed a technique for detecting the enterotoxin A gene (sea) using a loop-mediated isothermal amplification (LAMP) that amplified DNA with high specificity, efficiency and rapidity under isothermal amplifications conditions using a set of four specially designed primers and a DNA polymerase with strand displacement activity. In this study, we use LAMP and PCR for detection specificity and limit of detections. The specificity of LAMP was comparable to that conventional PCR method. The LAMP and PCR method correctly identified enterotoxin A gene (sea) of Staphylococcus aureus ATCC 13565 but did not detect other 15 non-Staphylococcus strains. Limit of detections of LAMP, the assay for direct detection of S.aureus in pure culture was 10⁴ CFU per milliliter while PCR showed 10³ CFU per milliliter. Afterward, the methods were employed for the detection S. aureus in pork samples to assess efficiencies of both methods. Results obtained show that LAMP was able to detect up to 10³ CFU per gram of pork sample while PCR could detect only 10⁴ CFU per gram of pork sample after incubation in TSB for 6 hours. Therefore it is obvious that LAMP is 10 fold sensitive for the detection of enterotoxin A gene in pork seeding sample than PCR.