Abstract: In this paper, a simple, rapid and sensitive method for the detection of Staphylococcus aureus based on color determination was established by using loop-mediated isothermal amplification (LAMP). LAMP primers were designed based on the specific target gene SAR0395 of S. aureus, and a visualized LAMP reaction system was built. The optimized conditions were determined as follows: inner primers (FIP and BIP), 1.6 μmol/L; outer primers (F3 and B3), 0.2 μmol/L; MgSO4, 4.0 mmol/L; dNTPs, 1.0 mmol/L, Bst 2.0 WarmStart? DNA polymerase, 0.4 U/μL; hydroxynaphthol blue, 120 μmol/L; and amplification at 60 ℃ for 60 min. Two loop primers (LF and LB) added to the LAMP system could reduce the reaction time to 20 min. After 60 minutes of reaction, the sensitivity of the LAMP assay was 0.010 3 fg/μL for genomic DNA and 1.9 CFU/mL for colonies. The specificity and reliability were confirmed by using 46 S. aureus and 24 non-S. aureus strains. The LAMP assay established in this study provides a new technique for rapid and visual detection of S. aureus.

Key words: visualization, loop-mediated isothermal amplification, detection, Staphylococcus aureus, hydroxynaphthol blue