Rapid and reliable loop-mediated isothermal amplification method for detecting streptococcus agalactiae

Streptococcus agalactiae (group B Streptococcus, GBS) is the leading cause of neonatal sepsis and meningitis and an important pathogen in elderly patients and those with underlying diseases. The diagnosis of GBS infections is primarily based on culture of GBS. Some clinical laboratories perform the Christie-Atkins-Munch-Peterson (CAMP) test for discrimination of GBS from other streptococci. Here, we developed a rapid GBS identification method, i.e., the loop-mediated isothermal amplification (LAMP) method for detecting the cfb gene encoding the CAMP factor. This method detected at least 4 copies of the cfb gene in GBS under isothermal conditions with in a short time (65°C, within 90 min). No inappropriate amplification of nucleotide by this method was observed when the chromosomal DNA of 17 streptococci and enterococci species, other than GBS, were used as templates. In this investigation, we successfully developed a LAMP method for rapid and highly sensitive detection of GBS, which provides a beneficial alternative to the conventional CAMP test.