An evaluation of a rapid real time polymerase chain reaction assay for detection of group B streptococcus as part of a neonatal group B streptococcus prevention strategy.
OBJECTIVE
To evaluate the sensitivity, specificity, and feasibility of a rapid real-time polymerase chain reaction (PCR) test for group B streptococcus (GBS) completed during labour, compared with the standard culture test performed at 35 to 37 weeks' gestation.


METHODS
Women presenting to the maternity unit for term vaginal delivery had two vaginal/rectal samples collected. One swab was tested using a rapid PCR method (IDI-Strep B, Infectio Diagnostic [IDI] Inc., Sainte-Foy QC ), and the other was cultured after enrichment (intrapartum culture). Comparisons were made between these results and those of a culture-based screen at 35 to 37 weeks' gestation.


RESULTS
Of the 190 women enrolled, 85% had results of the standard screen at 35 to 37 weeks available for comparison. The sensitivity and specificity of the standard 35- to 37-week screen were 84.3% (95% confidence interval [CI], 71.4-93.0) and 93.2% (95% CI 86.5-97.2) respectively, whereas the sensitivity and specificity of the rapid PCR were 90.7% (95% CI 79.7-96.9) and 97.6% (95% CI 93.1-99.5), respectively. The median reporting time for the rapid PCR test was 99 minutes (range 50-255). Results were available more than four hours before delivery in 81% of cases.


CONCLUSIONS
In this Canadian centre, a rapid PCR test done at the time of labour (IDI-Strep B) demonstrated high sensitivity and specificity, comparable to the 35- to 37-week screen. The time to reporting results was acceptably short, allowing for timely administration of intrapartum prophylactic antibiotics.
Department of Obstetrics and Gynaecology, Children's and Women's Health Centre of British Columbia, Vancouver BC; Women's Health Research Institute, Children's and Women's Health Centre of British Columbia, Vancouver BC.
Deborah
D
Money
Vaccine Evaluation Centre, Children's and Women's Health Centre of British Columbia, Vancouver BC.
Simon
S
Dobson
Department of Obstetrics and Gynaecology, Children's and Women's Health Centre of British Columbia, Vancouver BC.
Lesley
L
Cole
Department of Obstetrics and Gynaecology, Children's and Women's Health Centre of British Columbia, Vancouver BC.
Eda
E
Karacabeyli
Division of Microbiology, Department of Pathology and Laboratory Medicine, Children's and Women's Health Centre of British Columbia, Vancouver BC.
Edith
E
Blondel-Hill
Clinical Research Support Unit, Child and Family Research Institute, Vancouver BC.
Ruth
R
Milner
Division of Microbiology, Department of Pathology and Laboratory Medicine, Children's and Women's Health Centre of British Columbia, Vancouver BC.
Eva
E
Thomas
D000328:Adult; D004269:DNA, Bacterial / Q000302:isolation & purification; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000517:prevention & control*; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000382:microbiology; D012007:Rectum / Q000382:microbiology; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000517:prevention & control*; D013292:Streptococcus agalactiae / Q000235:genetics; D014621:Vagina / Q000382:microbiology; D055815:Young Adult
D004269:DNA, Bacterial