title: Loop-mediated isothermal amplification assay for rapid detection of Streptococcus agalactiae (group B streptococcus) in vaginal swabs - a proof of concept study.
abstract: OBJECTIVE
  Neonatal sepsis caused by Streptococcus agalactiae [group B streptococcus (GBS)] is a life-threatening condition, which is preventable if colonized mothers are identified and given antibiotic prophylaxis during labour. Conventional culture is time consuming and unreliable, and many available non-culture diagnostics are too complex to implement routinely at point of care. Loop-mediated isothermal amplification (LAMP) is a method that, enables the rapid and specific detection of target nucleic acid sequences in clinical materials without the requirement for extensive sample preparation.
  
  
  METHODS
  A prototype LAMP assay targeting GBS sip gene is described.
  
  
  RESULTS
  The assay was 100 % specific for GBS, with a limit of detection of 14 genome copies per reaction. The clinical utility of the LAMP assay for rapid direct molecular detection of GBS was determined by testing a total of 157 vaginal swabs with minimal sample processing using a rapid lysis solution. Compared to a reference quantitative real-time PCR assay, the direct LAMP protocol had a sensitivity and specificity of 95.4 and 100 %, respectively, with positive and negative predictive values of 100 and 98.3 %, respectively. Positive and negative likelihood ratios were infinity and 0.05, respectively. The direct LAMP method required a mean time of 45 min from the receipt of a swab to generation of a confirmed result, compared to 2 h 30 min for the reference quantitative real-time PCR test.
  
  
  CONCLUSIONS
  The direct LAMP protocol described is easy to perform, facilitating rapid and accurate detection of GBS in vaginal swabs. This test has a potential for use at point of care.
authors.affiliation: Regional Virus Laboratory, Department of Microbiology, Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: James Patrick
authors.initials: JP
authors.lastname: McKenna
authors.affiliation: Regional Virus Laboratory, Department of Microbiology, Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Ciara
authors.initials: C
authors.lastname: Cox
authors.affiliation: Regional Virus Laboratory, Department of Microbiology, Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Derek John
authors.initials: DJ
authors.lastname: Fairley
authors.affiliation: Regional Virus Laboratory, Department of Microbiology, Belfast Health and Social Care Trust, Belfast, UK.|Centre for Experimental Medicine, Queens University Belfast, Belfast, UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Burke
authors.affiliation: Centre for Experimental Medicine, Queens University Belfast, Belfast, UK.|Royal Belfast Hospital for Sick Children, Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Shields
authors.affiliation: Regional Virus Laboratory, Department of Microbiology, Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Watt
authors.affiliation: Regional Virus Laboratory, Department of Microbiology, Belfast Health and Social Care Trust, Belfast, UK.
authors.forename: Peter Valentine
authors.initials: PV
authors.lastname: Coyle
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics; D017931:DNA Primers; D000068598:Data Accuracy; D005260:Female; D016680:Genome, Bacterial; D006801:Humans; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D019095:Point-of-Care Systems; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000235:genetics / Q000302:isolation & purification*; D013696:Temperature; D014621:Vagina / Q000382:microbiology*
chemical_list: D000942:Antigens, Bacterial; D017931:DNA Primers; C414463:SIP protein, Streptococcus group B