Short communicationRapid detection of methicillin-resistant Staphylococcus aureus in pork using a nucleic acid-based lateral flow immunoassay

- The mecA gene was used as the specific maker for the identification of MRSA.
- Lateral flow immunoassay (LFI) strip was applied to test the PCR products.
- PCR-LFI assay exhibited good performance on both sensitivity and specificity.
- MRSA were successfully detected from imported pork products using PCR-LFI.

Methicillin-resistant Staphylococcus aureus (MRSA) is considered as one of the leading causes of food poisonings worldwide. Due to the high prevalence and extensive challenges in clinical treatment, a rapid and accurate detection method is required to differentiate MRSA from other S. aureus isolated from foods. Since the methicillin resistance of S. aureus is due to the acquisition of the mecA gene from staphylococcal chromosome cassette, the presence of the mecA gene is interpreted as a marker for the identification of MRSA. In this study, a low-cost lateral flow immunoassay (LFI) strip was used to detect the mecA amplicons subsequent to polymerase chain reaction (PCR). The specificity of this PCR-LFI assay was tested between MRSA and methicillin-susceptive S. aureus. Both the test line and control line were shown up on the LFI strip for MRSA, whereas only the control line developed for methicillin-susceptive S. aureus. The detection limit of PCR-LFI assay was 20 fg for genomic DNA (100 times more sensitive than gel electrophoresis) and 2 × 100 CFU per 100 g of pork products after enrichment at 37 °C for 48 h. The total detection time of using LFI was 3 min, which was faster than the conventional electrophoresis (~ 45 min). With the performance of PCR-LFI, 7 out of 42 S. aureus isolates were identified to be MRSA from imported pork products, which was consistent to the standardized minimum inhibitory concentration assay. This mecA-based PCR-LFI strip can be used for rapid and accurate detection of MRSA isolated from commercial pork products.