title: First-trimester group B Streptococcus colonization of the cervix: a risk factor for maternal colonization at term?
abstract: OBJECTIVE
  To identify the prevalence of first-trimester cervical group B Streptococcus (GBS) colonization in routine obstetric patients and whether a relationship exists between first-trimester cervical GBS colonization and maternal GBS bacteriuria or GBS colonization at term.
  
  
  METHODS
  An institutional review board-approved prospective, cohort study was performed. The study population included consecutively recruited, unselected obstetric patients who delivered at our medical center, presented for care in thefirst trimester and were followed for the duration of their pregnancies. Each patient consented to have an extra culture swab for GBS status obtained at the time of her first prenatal visit when a routine examination was performed. Urine and third-trimester culture data were also collectedfrom each study subject.
  
  
  RESULTS
  Of the 90 women with complete delivery data, 17 (19%) hadfirst-trimester cervical cultures positive for GBS. Women with first-trimester cervical GBS colonization were more likely to have third-trimester colonization on screening cultures than were women whose initial cultures were negative (35% vs. 14%, p = 0.05). The sensitivity of a GBS-positive cervical culture for detecting the coexisting presence of GBS bacteriuria was 38%, with a positive predictive value (PPV) of 31% and negative predictive value of 89%. When the outcome of interest was expanded to include GBS bacteriuria or third trimester colonization, the PPV of a positive cervical culture increased to 73%.
  
  
  CONCLUSIONS
  First-trimester GBS colonization of the cervix may be as sensitive as antepartum GBS bacteriuria, an established risk factor, for predicting maternal GBS colonization at term.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Burns and Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA.
authors.forename: Lissa C
authors.initials: LC
authors.lastname: Daimaru-Enoki
authors.forename: Margie
authors.initials: M
authors.lastname: Morgan
authors.forename: W Stephen
authors.initials: WS
authors.lastname: Nichols
authors.forename: Neil S
authors.initials: NS
authors.lastname: Silverman
mesh_terms: D000328:Adult; D001437:Bacteriuria / Q000453:epidemiology; D002584:Cervix Uteri / Q000382:microbiology*; D015331:Cohort Studies; D015169:Colony Count, Microbial; D005260:Female; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D018566:Pregnancy, High-Risk; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D013290:Streptococcal Infections / Q000150:complications* / Q000453:epidemiology; D013292:Streptococcus agalactiae / Q000254:growth & development / Q000302:isolation & purification*