Development and application of multiple polymerase spiral reaction (PSR) assays for rapid detection of methicillin resistant Staphylococcus aureus and toxins from rice and flour products

Methicillin-Resistant Staphylococcus aureus (MRSA) is an important foodborne pathogen and produces a variety of toxins causing serious illnesses. This study aimed at developing a rapid detection assay for MRSA and toxins targeting on two housekeeping genes (mecA and femA) and 5 virulence factors (sea, seb, sec, see and pvl) using the polymerase spiral reaction (PSR), compared with PCR. For naked-eye result inspection, calcein was added and the PSR reaction can be completed at 65?C within 60 min. The PSR assay was subjected to optimization, evaluation, and application in 3 different types of food sample made from rice and flour, designated rice and flour product. The limit of detection of PSR assay for the mecA, femA, sea, seb, sec, see and pvl genes was 4.2 pg/mu L, 0.42 pg/mu L, 630 pg/mu L, 63 pg/mu L, 12.3 pg/mu L, 1.015 pg/mu L and 53 pg/mu L, respectively, which was higher than the sensitivity of PCR. In rice and flour products, the detection limit of PSR assay was 10(4) CFU/mL for mecA, and 10(3) CFU/mL for femA, sea, seb, sec, see and pvl genes. In conclusion, optimized PSR assay serves as an efficient tool for rapid, cost-effective and accurate testing of MRSA and is suitable for point-of-care detection.