Rapid Detection of Streptococcus agalactiae Infection Using a Loop-Mediated Isothermal Amplification Method

Abstract

Background: Streptococcus agalactiae colonization in pregnant women leads to prenatal and neonatal infections worldwide; thus, early detection is very crucial. Objectives: Development of a rapid detection method for S. agalactiae. Methods: Genomic DNA of cultured S. agalactiae was prepared and loop-mediated isothermal amplification (LAMP) primers were designed based on the cAMP gene in bacteria. The optimum primer set was selected based on the reaction speed and specificity. The reaction result was monitored visually. The sensitivity and specificity of the LAMP method were evaluated and compared with polymerase chain reaction (PCR) method. Results: Using the optimum primer set the reaction can be completed in 40 minutes at 63°C in a water bath. The LAMP assay was 10 - 100 times more sensitive than PCR, with a detection limit of 10 CFU/mL of S. agalactiae. Forty vaginal swab were examined by LAMP, and the specificity was 100%. Conclusions: Thus, for S. agalactiae detection, the LAMP method is a valuable diagnostic tool, with easy, rapid, visual, accurate, and sensitive advantages.