Abstract: A rapid assay was developed for the detection of mecA and spa gene present in methicillin-resistant Staphylococcus aureus (MRSA) using loop-mediated isothermal amplification (LAMP). Staphylococcus aureus and other relevant bacteria were detected for their mecA and spa genes by both polymerase chain reaction (PCR) and LAMP methods. Gene amplification was successfully achieved by LAMP within 60 min when the temperature was held at 64 ℃, and the results were consistent results with those of the conventional PCR methods. The limits of detection of the LAMP method for mecA and spa genes were identified by agarose gel electrophoresis to be 102 and 10 cells per tube and observed by naked eyes to be 103 and 10 cells per tube respectively. The LAMP method was then applied to artificially polluted raw milk, and gave identical results with the traditional PCR methods. LAMP can rapidly detect mecA and spa genes, thus providing an applicable assay for detecting MRSA in raw milk.

Key words: loop-mediated isothermal amplification (LAMP), mecA gene, methicillin-resistant Staphylococcus aureus (MRSA), naked-eye observation, spa gene