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Rapid detection of methicillin-resistant Staphylococcus aureus in pork using a nucleic acid-based lateral flow
Hongwei Zhang1, Luyao Ma2, Lina Ma2
1Key Laboratory of Food Nutrition, Safety Ministry of Education of China, Tianjin University of Science and Technology, Tianjin 300457, China; Food, Nutrition and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Abstract:
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 20fg for genomic DNA (100 times more sensitive than gel electrophoresis) and 2×100CFU per 100g of pork products after enrichment at 37°C for 48h. The total detection time of using LFI was 3min, which was faster than the conventional electrophoresis (~45min). 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.
Insights
A new, low-cost PCR-LFI assay rapidly and accurately detects methicillin-resistant Staphylococcus aureus (MRSA) in food. This method identifies the mecA gene, crucial for differentiating MRSA from susceptible strains in pork products.
Area of Science:
- Food safety and microbiology
- Molecular diagnostics
- Antimicrobial resistance
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of global foodborne illness.
- Accurate and rapid detection methods are essential for differentiating MRSA in food products.
- The mecA gene is a reliable marker for identifying MRSA due to its role in methicillin resistance.
Purpose of the Study:
- To develop and evaluate a low-cost lateral flow immunoassay (LFI) strip for detecting the mecA gene.
- To assess the specificity and sensitivity of the PCR-LFI assay for MRSA identification.
- To determine the assay's effectiveness in detecting MRSA in imported pork products.
Main Methods:
- Developed a polymerase chain reaction (PCR) combined with a lateral flow immunoassay (LFI) strip.
- Tested the specificity of the PCR-LFI assay using MRSA and methicillin-susceptible S. aureus isolates.
- Determined the detection limit using genomic DNA and spiked pork products, comparing it to gel electrophoresis.
Main Results:
- The PCR-LFI assay demonstrated high specificity, with distinct results for MRSA versus susceptible strains.
- Achieved a detection limit of 20fg for genomic DNA and 2×100 CFU/100g in pork after enrichment.
- The total detection time using LFI was significantly reduced to 3 minutes compared to conventional methods.
- Identified 7 out of 42 S. aureus isolates as MRSA in imported pork, consistent with MIC assays.
Conclusions:
- The developed mecA-based PCR-LFI strip offers a rapid, accurate, and cost-effective method for MRSA detection.
- This assay is suitable for identifying MRSA in commercial pork products, enhancing food safety surveillance.
- The PCR-LFI approach provides a valuable tool for differentiating MRSA from S. aureus in food matrices.
