title: Evaluation of the Strep B OIA test compared to standard culture methods for detection of group B streptococci.
abstract: OBJECTIVE
  This study evaluated the accuracy of the commercial product Strep B OIA (optical immunoassay) compared to the standard agar and broth culture methods for detecting vaginal colonization with group B streptococcus (GBS).
  
  
  METHODS
  Preoperative vaginal cultures were obtained from 141 nonpregnant gynecological patients undergoing major gynecologic surgery. Major gynecologic surgery was defined as benign gynecologic, gyne-oncology, and urogynecologic procedures. The results of the Strep B OIA test were compared to the results obtained from SXT agar (selective for GBS), colistin-nalidixic acid ((CNA) agar, and Todd-Hewitt broth cultures.
  
  
  RESULTS
  The prevalence of vaginal GBS colonization in this population was 20.6%. The sample sensitivity and specificity of the OIA method were 58.6% and 85.7%, respectively. These values are lower than the sensitivity and specificity of 85.4% and 91.5%, respectively, given in the OIA package insert. Although the sample negative predictive value was fairly high (88.9%), the positive predictive value was low (51.5%).
  
  
  CONCLUSIONS
  Although a previous study stated that the product Strep B OIA reduces the time required to obtain results (30 minutes versus days) and can, therefore, function as a useful diagnostic tool in the management of early-onset GBS disease, the present study's finding of low sensitivity and low positive predictive value indicates that this test may have very limited clinical value.
authors.affiliation: Department of Obstetrics and Gynecology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612-3833, USA.
authors.forename: J Y
authors.initials: JY
authors.lastname: Song
authors.forename: L L
authors.initials: LL
authors.lastname: Lin
authors.forename: S
authors.initials: S
authors.lastname: Shott
authors.forename: N
authors.initials: N
authors.lastname: Kimber
authors.forename: J
authors.initials: J
authors.lastname: Tangora
authors.forename: A
authors.initials: A
authors.lastname: Cohen
authors.forename: A
authors.initials: A
authors.lastname: Wells
authors.forename: M
authors.initials: M
authors.lastname: Maezes
authors.forename: A
authors.initials: A
authors.lastname: Aroutcheva
authors.forename: S
authors.initials: S
authors.lastname: Faro
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000592:standards; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000517:prevention & control; D013292:Streptococcus agalactiae / Q000302:isolation & purification*; D014621:Vagina / Q000382:microbiology*; D016585:Vaginosis, Bacterial / Q000175:diagnosis*