title: Optimization of a rapid diagnostic test for detection of group B streptococcus from antepartum patients.
abstract: We analyzed the performance of a new rapid diagnostic test for use in determining group B streptococcus colonization in pregnancy. Vaginal-rectal specimens were compared by the rapid test, a commercial laboratory culture result, and an in-house culture. Of 150 patient samples, 72 were positive by the rapid test, giving a prevalence of 48.0% versus 24.7% by traditional culture. Characterization of these results showed cross-reactivity with Enterococcus. The addition of bacitracin reduced this interference, and when reanalyzed, a colonization rate of 31.3% was found (P = 0.3961, chi-square), as well as a sensitivity of 100% (95% confidence interval [CI] 89.1-100) and a specificity of 93.6% (95% CI 86.9-97.2). The addition of bacitracin greatly improves the reliability of this diagnostic test and demonstrates a novel approach to reduce interference. An accurate determination of the test's sensitivity and specificity, however, awaits enrollment of the remaining subjects.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center, Houston, TX 77030, USA. jonathan.p.faro@uth.tmc.edu
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Faro
authors.forename: Karen
authors.initials: K
authors.lastname: Bishop
authors.forename: Gerald
authors.initials: G
authors.lastname: Riddle
authors.forename: Allan
authors.initials: A
authors.lastname: Katz
authors.forename: Sebastian
authors.initials: S
authors.lastname: Faro
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D003429:Cross Reactions; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis* / Q000382:microbiology; D012007:Rectum / Q000382:microbiology; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000302:isolation & purification*; D014621:Vagina / Q000382:microbiology