Detection of group B Streptococcus using taqman realtime PCR method in suspected meningitis infants

Abstract

Group B streptococcus (GBS) remains the predominant bacterial pathogen of meningitis in the neonatal population worldwide. However, in Vietnam, whereas the detection rate of GBS colonizing pregnant women had been studied occasionally, such data of the neonatal population remains uncertain. To accurately confirm diagnosed meningitis and retrieve data on GBS prevalence, this study developed a real-time PCR method to detect GBS species in CSF samples of children under 1 month old. DNA fragment to be detected is the cfb gene encoding CAMP factor using sequence specific TaqMan fluorescent probe. Assay sensitivity was verified as 3.64 × 102 CFU/mL for a threshold cycle of approximately 34 – 35 in a 10 μL reaction mixture. No cross reactions with other species was detected. A total of 240 clinical CSF specimens from children under 1 month old with probable meningitis from 2015 to 2017, whose results were negative for three common meningitis bacterial pathogens Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae, underwent real-time PCR. Four samples were found to be GBS positive (1.67%). In conclusion, using real-time PCR is a practical, highly sensitive method for identification of GBS with rapid time to result. Furthermore, as to date GBS vaccine are still in development, more systematic estimates should be undertaken to gain more insight to this potential infectious etiology. Keywords: GBS, meningitis, neonates, real-time PCR, cfb gene