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Nicholas McManus

Nicholas McManus

Is Bacterial Vaginosis an STD?

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First...let's set the stage...

Bacterial vaginosis (BV) is characterized by a shift in vaginal flora away from Lactobacillus species toward a more diverse bacterial spectrum such as Gardenella vaginalis, Mobiluncus curtisii, M. mulieris, other anaerobic bacteria and/or Mycoplasma hominis.1 This shift in the vaginal microbiome results in alterations to the normal vaginal environment with production of amines by the new bacterial flora resulting in a rise in vaginal pH > 4.5.2

BV is the most common vaginal infection of childbearing age, accounting for up to 50% of all causes of vaginal discharge.3 Prevalence in the general population is measured to be 20% in women aged 14-49 years old, and even higher in certain populations. 50% of patients with BV are asymptomatic in studies.3,4 The health consequences of BV are well established in literature and include preterm delivery, low birth weight, chorioamnionitis, endometritis, post-surgical infection, infertility and is associated with an increased risk of precancerous cervical intraepithelial neoplasia (CIN) or squamous intraepithelial lesions (SIL) with an odds ratio of 1.51 (95% CI 1.24-1.83).5

Factors associated with the development of BV includes obesity, cigarette smoking, douching, high fat diets, and sexual activity. Menstruation duration less than 3 days, dysmenorrhea or the use an intrauterine device was all associated with BV prevalence.6 Race and Ethnicity appears to play a factor as well with African-American women showing the highest prevalence of up to 51% in studies.4 Interestingly, BV has not been shown to be associated with chronic medical conditions such as Diabetes or immunosuppression.

Despite 60 years of research defining these associated risk factors, true causation has yet to be defined. While many theories have been described in literature, including BV specific pathogens, changes in normal vaginal flora and host immune response; these theories fail to reliably explain exact etiology.7

So….it is possible that BV is sexually transmitted?

Well, the answer is probably not that simple because sex isn’t that simple. In the last 10 years, research has started to focus more on the correlation of sexual activity and Bacterial Vaginosis, and while correlation does not equal causation, the role of unprotected sexual activity in the development of BV has been well described in many prospective studies.

Some theories suggest that factors of sexual activity such as the bactericidal effects of vaginal lubricants, or the alkaline pH of semen may alter the natural balance of vaginal bacterial flora, resulting in the development of BV with a subsequent increased risk of STI transmission.8 However, multiple studies have shown that oral sex, anal sex, women who have sex with a new partner and women who have sex with women have all been found to be risk factors for the development of BV.8,9,10 In a systematic review and meta-analysis of 43 studies, BV was associated with a higher prevalence in women with new or multiple male partners with a relative risk of 1.6 (95% CI, 1.5-1.8) and an even higher prevalence women with a female partner (risk ration 2.0, 95% CI 1.7-2.3). In women who use condoms, the relative risk was much lower at 0.8 (95% CI 0.8-0.9) and was associated with sustained normal vaginal flora over time, suggesting that the epidemiological profile of BV is similar to that of established STD’s.9,11 This suggests that BV associated bacteria may truly be associated with unprotected sexual behavior and the failure of BV to resolve in women, hypothesizing that colonization of male genitalia may serve as a reservoir for re-infection of female partners.

If fact, research has shown that women who have sex with women colonize each other with unique strains of lactobacillus through sexual practices.8 Data from a 24-month cohort study of 298 women who have sex with women found that receptive oral sex, BV symptom onset, and exposure to a new sexual partner positively influenced BV acquisition. Even more interesting from this study is that women with a BV-negative partner had a reduced risk of BV acquisition by a whopping 74%.12 This specific situation almost certainly represents the features of an STD in the setting of BV associated bacteria.Still, BV is difficult to define as an STD, mainly because a similar symptomatic disease entity has not been described in males.

BV is not only associated with sexual activity. Other studies have shown that BV is associated with an increased risk sexually transmitted infections including HIV, HSV-2, Gonorrhea, Chlamydia, Trichomoniasis, Syphilis and HPV.

HSV-2 infected women were found to have a 55% higher risk of BV than those who were uninfected.13 A systematic review of 23 cohort studies estimated that the risk of HIV transmission was increased 60% in patients with BV.15 One theory to explain this includes an increased adherence and survival of HIV at the higher vaginal pH seen in BV. But again, correlation does not prove causation. Either way, I am starting to see a theme here….

How about Chlamydia and Gonorrhea? BV is associated with sexual behavior risk factors similar to those associated with Chlamydiaand there is evidence from two randomized trials that screening and treating asymptomatic women with BV reduces the risk of acquiring a Chlamydia and Gonorrhea infection.15,16

One epidemiologic characteristic to keep in mind is that Chlamydia is usually asymptomatic (~75% in women, ~50% in men) while gonorrhea is asymptomatic in up to 75% of men and 70-90% of women, providing an important reservoir of infection.17,18 In a cohort study of sex workers in Kenya, the absence of lactobacilli was associated with an increased risk of Gonorrhea, but not Chlamydia with a hazard ratio of 1.7.19 In a United States based cohort study of 535 women, a bacterial vaginosis (Nugent score) of > 8 was associated with a 2.7 fold increased in STI.4

A list of studies outlining risk of co-infection with Chlamydia or Gonorrhea are summarized below.

Although the epidemiological profile of BV seems to be similar to chlamydia and gonorrhea, the evidence is insufficiently conclusive to consider BV as an STI, but the weight of evidence is certainly supportive. Regardless,the effect of BV on chlamydia or gonorrhea is an interesting area for future research. One could consider the rationale for treatment of BV co-infections in otherwise high-risk patients with poor follow-up.

Article peer reviewed by:

Caleb Bryant, PharmD

Caleb Bryant, PharmD

Emergency Department Pharmacist

References

  1. Bautista CT, Wurapa EK, et al. Association of Bacterial Vaginosis With Chlamydia and Gonorrhea Among Women in the U.S. Army. Am J Prev Med. 2017 May;52(5):632-639
  2. Fredricks DN, Fiedler TL, Marrazzo JM. Molecular identification of bacteria associated with bacterial vaginosis. N Engl J Med 2005; 353:1899.
  3. Morris M, Nicoll A, Simms I, et al. Bacterial vaginosis: a public health review. BJOG 2001; 108:439.
  4. Allsworth JE, Peipert JF. Prevalence of bacterial vaginosis: 2001-2004 National Health and Nutrition Examination Survey data. Obstet Gynecol 2007; 109:114.
  5. Gillet E, Meys JF, Verstraelen H, et al. Association between bacterial vaginosis and cervical intraepithelial neoplasia: systematic review and meta-analysis. PLoS One 2012; 7:e45201.
  6. Li XD, Wang CC, Zhang XJ, Gao GP, Tong F, Li X, et al. Risk factors for bacterial vaginosis: results from a cross-sectional study having a sample of 53,652 women.Eur J Clin Microbiol Infect Dis. 2014;33:1525–32. doi: 10.1007/s10096-014-2103-1
  7. Turoviskiy T, Noll KS, et al. 2011. The etiology of bacterial vaginosis. J Appl Microbiol. 2011. 110(5): 1105-1128.
  8. Marraazzo JM. Interpreting the epidemiology and natural history of bacterial vaginosis: are we still confused? Anaerobe. 2011; 17(4):196-90.
  9. Fethers KA, Dairley CK, et la. Sexual risk factors and bacterial vaginosis: a systematic review and meta-analysis. Clin Infect Dis. 2008;47(11):1426-35
  10. Brotman RM, Erbelding EJ, Jamshidi RM, Klebanoff MA, Zenilman JM, Ghanem KG. Findings associated with recurrence of bacterial vaginosis among adolescents attending sexually transmitted diseases clinics.Pediatr Adolesc Gynecol. 2007;20:225–31. doi: 10.1016/j.jpag.2006.11.009.
  11. Schwebke JR, Desmond R. Risk factors for bacterial vaginosis in women at high risk for sexually transmitted diseases. Sex transm Dis. 2005; 32(11):654-8.
  12. Vodstrcil LA, Walker SM, Hocking JS, Law M, Forcey DS, Fehler G, et al. Incident bacterial vaginosis (BV) in women who have sex with women is associated with behaviors that suggest sexual transmission of BV.Clin Infect Dis. 2015;60:1042–53
  13. Esber A, Vicetti Miguel RD, Cherpes TL, Klebanoff MA, Gallo MF, Turner AN. Risk of Bacterial Vaginosis Among Women With Herpes Simplex Virus Type 2 Infection: A Systematic Review and Meta-analysis.J Infect Dis. 2015;212:8–17. doi: 10.1093/infdis/jiv017.
  14. Atashili J, Poole C, Ndumbe PM, Adimora AA, Smith JS. Bacterial vaginosis and HIV acquisition: a meta-analysis of published studies. 2008;22(12):1493–501. doi: 10.1097/QAD.0b013e3283021a37.
  15. Nilsson U, Hellberg D, Shoubnikova M, Nilsson S, Mårdh PA. Sexual behavior risk factors associated with bacterial vaginosis and Chlamydia trachomatis infection.Sex Transm Dis. 1997;24:241–6. doi: 10.1097/00007435-199705000-00001
  16. Bautista CT, Wurapa E, et al. Bacterial vaginosis: a synthesis of the literature on etiology, prevalence, risk factors, and relationship with chlamydia and gonorrhea infections. Mil Med Res. 2016;3:4 doi: 1186/s40779-016-0074-5
  17. Dielissen PW, Teunissen DA, Lagro-Janssen AL. Chlamydia prevalence in the general population: is there a sex difference? a systematic review.BMC Infect Dis. 2013;13:534. doi: 10.1186/1471-2334-13-534. 
  18. Walker CK, Sweet RL. Gonorrhea infection in women: prevalence, effects, screening, and management.Int J Womens Health. 2011;3:197–206.
  19. Martin HL, Richardson BA, Nyange PM, Lavreys L, Hillier SL, Chohan B, et al. Vaginal lactobacilli, microbial flora, and risk of human immunodeficiency virus type 1 and sexually transmitted disease acquisition.J Infect Dis. 1999;180:1863–8. doi: 10.1086/315127.
  20. Joesoef MR, Wiknjosastro G, Norojono W, Sumampouw H, Linnan M, Hansell MJ, et al. Coinfection with chlamydia and gonorrhoea among pregnant women and bacterial vaginosis.Int J STD AIDS. 1996;7:61–4. doi: 10.1258/0956462961917096.
  21. Keane FE, Thomas BJ, Whitaker L, Renton A, Taylor-Robinson D. An association between non-gonococcal urethritis and bacterial vaginosis and the implications for patients and their sexual partners.Genitourin Med. 1997;73:373–7.
  22. Wiesenfeld HC, Hillier SL, et al. Bacterial Vaginosis is a strong predictor of Neisseria gonorrhoeae and Chlamydia trachomatis infection. Clinical Infectious Diseases. 2003; 36(5):663-669 https://doi.org/10.1086/367658
  23. Ness RB, Kip KE, Soper DE, Hillier S, Stamm CA, Sweet RL, et al. Bacterial vaginosis (BV) and the risk of incident gonococcal or chlamydial genital infection in a predominantly black population.Sex Transm Dis. 2005;32:413–7. doi: 10.1097/01.olq.0000154493.87451.8d.
  24. Brotman RM, Klebanoff MA, Nansel TR, Yu KF, Andrews WW, Zhang J, et al. Bacterial vaginosis assessed by gram stain and diminished colonization resistance to incident gonococcal, chlamydial, and trichomonal genital infection.J Infect Dis. 2010;202:1907–15. doi: 10.1086/657320.
  25. Gallo MF, Macaluso M, Warner L, Fleenor ME, Hook EW, 3rd, Brill I, et al. Bacterial vaginosis, gonorrhea, and chlamydial infection among women attending a sexually transmitted disease clinic: a longitudinal analysis of possible causal links.Ann Epidemiol. 2012;22:213–20. doi: 10.1016/j.annepidem.2011.11.005.
  26. Allsworth JE, Peipert JF. Severity of bacterial vaginosis and the risk of sexually transmitted infection.Am J Obstet Gynecol. 2011;205:e1–6. doi: 10.1016/j.ajog.2011.02.060.
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