Rapid group B streptococci screening using a real-time polymerase chain reaction assay.
OBJECTIVE
To estimate the clinical performance characteristics of a real-time polymerase chain reaction (PCR) assay using vaginal/rectal swabs from antepartum (35-37 weeks of gestation) and intrapartum women.


METHODS
The assay evaluated is a qualitative, automated, real-time PCR test for the detection of group B streptococci, with results available in approximately 75 minutes. Enrollment in this multicenter clinical study occurred between October 2005 and January 2006. Vaginal/rectal swabs were analyzed by nursing personnel (intrapartum tests) or by laboratory technologists (all others). Polymerase chain reaction assay results were compared with culture using standard methods, including selective broth medium, and to a predicate nucleic acid amplification test.


RESULTS
Of 1,028 enrolled women, 234 were deemed ineligible, and 10 had unresolved test results. Of the 784 remaining women, valid PCR assay results were obtained on the first test attempt for 93.0%. Performance characteristics relative to culture were sensitivity 91.1%, specificity 96.0%, positive predictive value 87.8%, negative predictive value 97.1%, and accuracy 94.8%. These results exceeded those obtained using the predicate nucleic acid amplification test.


CONCLUSIONS
Performance characteristics of the PCR assay exceed the threshold recommended by the Centers for Disease Control and Prevention when compared with culture. The test is sufficiently robust to be performed for intrapartum patients in a point-of-care setting by medical professionals.


METHODS
II.
Phoenix Perinatal Associates, Obstetrix Medical Group of Phoenix, Phoenix, Arizona 85014, USA. rodney_edwards@pediatrix.com
Rodney K
RK
Edwards
Susan M
SM
Novak-Weekley
Patrick P
PP
Koty
Thomas
T
Davis
Leroy J
LJ
Leeds
Jeanne A
JA
Jordan
D001431:Bacteriological Techniques; D003199:Computer Systems; D005260:Female; D006801:Humans; D021141:Nucleic Acid Amplification Techniques; D019095:Point-of-Care Systems; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000382:microbiology*; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000382:microbiology*; D013292:Streptococcus agalactiae / Q000302:isolation & purification*