Bacterial vaginosis assessed by gram stain and diminished colonization resistance to incident gonococcal, chlamydial, and trichomonal genital infection

J Infect Dis. 2010 Dec 15;202(12):1907-15. doi: 10.1086/657320. Epub 2010 Nov 10.


Background: We sought to assess the relationship between bacterial vaginosis (BV) assessed by Gram stain and incident trichomonal, gonococcal, and/or chlamydial genital infection.

Methods: This longitudinal study included 3620 nonpregnant women aged 15-44 years who presented for routine care at 12 clinics in Birmingham, Alabama. Participants were assessed quarterly for 1 year. Vaginal smears were categorized by the Nugent Gram stain score (0-3, normal; 4-6, intermediate state; 7-10, BV). Pooled logistic regression was used to estimate the hazard ratios for the comparison of trichomonal, gonococcal, and chlamydial infection incidence in participants by Nugent score at the prior visit. Participants were censored at their first visit with a positive test result for trichomonal, gonococcal, and/or chlamydial infection.

Results: Of the 10,606 eligible visits, 37.96% were classified by BV and 13.3% by positive detection of trichomonal, gonococcal, and/or chlamydial infection. An intermediate state or BV at the prior visit was associated with a 1.5-2-fold increased risk for incident trichomonal, gonococcal, and/or chlamydial infection (adjusted hazard ratio [AHR] for intermediate state, 1.41 [95% confidence interval {CI}, 1.12-1.76]; AHR for BV, 1.73 [95% CI, 1.42-2.11]; P= .058 for trend). Estimates were similar for trichomonal-only, gonococcal-only, and chlamydial-only infection outcomes.

Conclusion: BV microbiota as gauged by Gram stain is associated with a significantly elevated risk for acquisition of trichomonal, gonococcal, and/or chlamydial genital infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adolescent
  • Adult
  • Alabama / epidemiology
  • Bacteriological Techniques / methods
  • Chlamydia Infections / epidemiology*
  • Female
  • Gentian Violet
  • Gonorrhea / epidemiology*
  • Humans
  • Incidence
  • Longitudinal Studies
  • Phenazines
  • Trichomonas Infections / epidemiology*
  • Vaginal Smears
  • Vaginosis, Bacterial / complications*
  • Vaginosis, Bacterial / diagnosis*
  • Young Adult


  • Gram's stain
  • Phenazines
  • Gentian Violet