Evaluation of the real-time fluorescence loop-mediated isothermal amplification assay for the detection of Streptococcus agalactiae.

Streptococcus agalactiae is a major pathogenic bacterium causing perinatal infections in humans. In the present study, a novel real-time fluorescence loop-mediated isothermal amplification technology was successfully developed and evaluated for the detection of S. agalactiae in a single reaction. Six specific primers were designed to amplify the corresponding six regions of fbs B gene of S. agalactiae, using Bst DNA polymerase with DNA strand displacement activity at a constant temperature for 60 min. The presence of S. agalactiae was indicated by the fluorescence in real-time. Amplification of the targeted gene fragment was optimized with the primer 1 in the current setup. Positive result was only obtained for Sa by Real-LAMP among 10 tested relevant bacterial strains, with the detection sensitivity of 300 pg/µl. Real-LAMP was demonstrated to be a simple and rapid detection tool for S. agalactiae with high specificity and stability, which ensures its wide application and broad prospective utilization in clinical practice for the rapid detection of S. agalactiae.