Rapid visualization and detection of Staphylococcus aureus based on loop-mediated isothermal amplification

Staphylococcus aureus is a common clinical bacterial pathogen that can cause a diverse range of infections. The establishment of a rapid and reliable assay for the early diagnosis and detection of S. aureus is of great significance. In this study, we developed a closed-tube loop-mediated isothermal amplification (LAMP) assay for the visual detection of S. aureus using the colorimetric indicator hydroxy naphthol blue (HNB). The LAMP reaction was optimized by adjusting the amplification temperature, the concentrations of Mg2+, dNTP, and HNB, and the incubation time. In the optimized reaction system, the specificity of LAMP for S. aureus was 100%. The results established that this method accurately identified S. aureus, with no cross-reactivity with 14 non-S. aureus strains. The limit of detection (LOD) of LAMP was 8 copies/reaction of purified plasmid DNA or 400 colony-forming units/reaction of S. aureus. Compared with conventional PCR, LAMP lowered the LOD by tenfold. Finally, 220 clinically isolated strains of S. aureus and 149 non-S. aureus strains were used to evaluate the diagnostic efficacy of LAMP (test accuracy, 99.46%). The findings indicated that LAMP is a reliable test for S. aureus and could be a promising tool for the rapid diagnosis of S. aureus infections.