Isothermal amplification assay for visual on-site detection of Staphylococcus aureus in Chevon

ABSTRACT The ability to rapidly detect pathogens in food is important from public health and food safety reasons. Traditional culture-based detection methods tend to be laborious, time consuming, technically demanding and may be limited due to their low sensitivity. Rapid detection methods for foodborne pathogens should be specific and sensitive to detect pathogens in low numbers. Sensitivity is important because a single pathogen present in food has the potential risk to cause infection. PCR and Real-time PCR are rapid, sensitive, and specific but require specific instruments and laboratory set-up. In the present study, a simple loop-mediated isothermal amplification (LAMP) assay was developed for rapid detection of Staphylococcus aureus. The LAMP assay was found to be ten times more sensitive than traditional end-point PCR with analytical sensitivity of 0.56 pg/μl and 5.6 pg/μl of DNA, respectively. In spiked chevon samples inoculated with S. aureus, the detection limit of LAMP and PCR assay was 3.3 × 105 CFU/g and 3.3 × 106 CFU/g, respectively, without enrichment. After enriching the samples for 6 h, the detection limit improved to 3.3 × 102 CFU/g and 3.3 × 104 CFU/g, respectively, indicating LAMP to be 100-fold more sensitive than PCR. The detection limit further improved to 3.3 CFU/g of meat after enrichment of 12 h. The developed LAMP was also found to be suitable when evaluated on field samples. The present study reports a simple LAMP assay for rapid visual detection of S. aureus which has potential for use in resource limited settings.