Isothermal recombinase polymerase amplification assay applied to the detection of group B streptococci in vaginal/anal samples.
BACKGROUND
Group B streptococcal infections are the leading cause of sepsis and meningitis in newborns. A rapid and reliable method for the detection of this pathogen at the time of delivery is needed for the early treatment of neonates. Isothermal amplification techniques such as recombinase polymerase amplification have advantages relative to PCR in terms of the speed of reaction and simplicity.


METHODS
We studied the clinical performance of recombinase polymerase amplification for the screening of group B streptococci in vaginal/anal samples from 50 pregnant women. We also compared the limit of detection and the analytical specificity of this isothermal assay to real-time PCR (RT-PCR).


RESULTS
Compared to RT-PCR, the recombinase polymerase amplification assay showed a clinical sensitivity of 96% and a clinical specificity of 100%. The limit of detection was 98 genome copies and the analytical specificity was 100% for a panel of 15 bacterial and/or fungal strains naturally found in the vaginal/anal flora. Time-to-result for the recombinase polymerase amplification assay was <20 min compared to 45 min for the RT-PCR assay; a positive sample could be detected as early as 8 min.


CONCLUSIONS
We demonstrate the potential of isothermal recombinase polymerase amplification assay as a clinically useful molecular diagnostic tool that is simple and faster than PCR/RT-PCR. Recombinase polymerase amplification offers great potential for nucleic acid-based diagnostics at the point of care.
Centre de recherche du CHU de Québec, Centre de recherche en infectiologie de l'Université Laval (CRI), Quebec, Canada;
Rana K
RK
Daher
Gale
G
Stewart
Maurice
M
Boissinot
Michel G
MG
Bergeron
D001003:Anal Canal / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry*; D005260:Female; D006801:Humans; D057230:Limit of Detection; D021141:Nucleic Acid Amplification Techniques / Q000379:methods; D019095:Point-of-Care Systems; D011247:Pregnancy; D045522:Recombinases / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013292:Streptococcus agalactiae / Q000235:genetics* / Q000302:isolation & purification; D014621:Vagina / Q000382:microbiology*
D004269:DNA, Bacterial; D045522:Recombinases; D004259:DNA-Directed DNA Polymerase