Conference Contribution Details
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Smith, T.J., O’Connor, L., Mullen, C., Clarke, C., Lahiff, S., Glynn, B., Keaney, T.
American Society of Microbiology 115th General Meeting
Real-time Detection of Group B Streptococcus in Pregnant Women using LAMP Technology.
New Orleans, Louisiana, USA
Conference Organising Committee Chairperson
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Background Maternal colonisation with Group B Streptococcus (GBS) is recognised as the most frequent cause of severe early onset infection in newborns. Culture-based screening and subsequent treatment has proven to be highly effective in lowering neonatal GBS disease. There is however a requirement for rapid diagnostic tests for GBS detection which can be performed in a labour-ward setting to ascertain the GBS status of women in labour, those in preterm labour or women who have not had prenatal care.  To address the need for a rapid test, the development of a real-time LAMP (loop-mediated isothermal amplification) assay for the detection of Group B Streptococcus was undertaken. LAMP is an attractive isothermal amplification technology for near patient testing applications due to the speed of the reaction and simple instrumentation requirements.   Methods A real-time LAMP assay was developed using the cfb gene target.  LAMP primers were designed using the Primer Explorer programme (version 4) to specifically target Group B Streptococcus. Specificity studies were performed using a panel of Group B Streptococcus strains, related Streptococci and other species commonly found in the human genital tract.  The LAMP amplification reaction (62°C for 30 minutes) was performed on the Roche LightCycler 480. PicoGreen™ was included in the reaction to allow real-time monitoring and to enable melt curve analysis. The real-time LAMP assay was evaluated on vaginal swab samples collected from 124 pregnant women undergoing routine pregnancy screening.    Results The LAMP assay specifically detected GBS. No cross reactions were observed when an extended exclusivity panel was tested. The limit of detection of the assay was determined by Probit Analysis and was found to be approximately 30 copies of target. Results for clinical samples tested showed that the LAMP assay results correlated 100% with culture results. Conclusions LAMP technology offers advantages over non-isothermal methods including less sophisticated equipment requirements and high specificity. The LAMP assay described here is a rapid, highly specific and sensitive method for the detection of GBS and could be adapted onto suitable instrumentation for near-patient setting. The development of robust, reliable, easy to perform near-patient tests will enable broader screening of at risk patients in the labour ward.
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