Evaluation of loop-mediated isothermal amplification method for detecting enterotoxin A gene of Staphylococcus aureus in pork.

Staphylococcus aureus is an important food-borne pathogen of humans due to ingestion of food containing enterotoxigenic strains. We evaluated the detection of S. aureus enterotoxin A gene (sea) using a loop-mediated isothermal DNA amplification (LAMP) method. Specificity of LAMP method was comparable to that of conventional PCR. Both methods correctly identified sea and did not detect 14 other non-Staphylococcus strains. Limit of detections of LAMP assay for direct detection of S. aureus was 10(4) cfu/ml while that of PCR was 10(3) cfu/ml. Both methods were employed for the detection of S. aureus spiked pork samples to assess their sensitivity. LAMP method was able to detect a minimum of 10(3) cfu/g while PCR 10(4) cfu/g of pork sample following incubation in tryptic soy broth for 6 hours. The LAMP assay allows a one-step identification of gene of interest without any specialized equipment and requires less time than conventional PCR, thus suggesting that the LAMP technique might be an appropriate alternative diagnostic method for detecting enterotoxin A gene of S. aureus in food sample.