Bacterial vaginosis

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Bacterial vaginosis
Classification and external resources

Micrograph of bacterial vaginosissquamous cells of the cervix covered with rod-shaped bacteria, Gardnerella vaginalis (arrows).
ICD-10B96, N76
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Bacterial vaginosis
Classification and external resources

Micrograph of bacterial vaginosissquamous cells of the cervix covered with rod-shaped bacteria, Gardnerella vaginalis (arrows).
ICD-10B96, N76

Bacterial vaginosis (BV) or less commonly vaginal bacteriosis[1] is a disease of the vagina caused by bacteria. According to the U.S. Centers for Disease Control and Prevention (CDC), risk factors for BV include douching and having new or multiple sex partners, although it is unclear what role sexual activity plays in the development of BV.[2][3] BV is caused by an imbalance of naturally occurring bacterial flora and is often confused with yeast infection (candidiasis) or infection with Trichomonas vaginalis (trichomoniasis), which are not caused by bacteria.[4][5]


Symptoms and signs

The most common symptom of BV is an abnormal homogeneous off-white vaginal discharge (especially after vaginal intercourse) that may be accompanied by an unpleasant (usually fishy) smell.[6] This malodorous discharge coats the walls of the vagina, and is usually without significant irritation, pain, or erythema (redness), although mild itching can sometimes occur. By contrast, the normal vaginal discharge will vary in consistency and amount throughout the menstrual cycle and is at its clearest at ovulation - about 2 weeks before the period starts. Some practitioners claim that BV can be asymptomatic in almost half of affected women,[7] though others argue that this is often a misdiagnosis.[8]


A healthy vagina normally contains many microorganisms; some of the common ones are Lactobacillus crispatus and Lactobacillus jensenii. Lactobacilli, particularly hydrogen peroxide-producing species, appear to help prevent other vaginal microorganisms from multiplying to a level where they cause symptoms. The microorganisms involved in BV are very diverse, but include Gardnerella vaginalis, Mobiluncus, Bacteroides, and Mycoplasma. A change in normal bacterial flora including the reduction of Lactobacilli, which may be due to the use of antibiotics or pH imbalance, allows more resistant bacteria to gain a foothold and multiply.

Although BV can be associated with sexual activity, there is no clear evidence of sexual transmission.[9] [10] It is possible for sexually inactive persons to get infected with bacterial vaginosis. Rather, BV is a disordering of the chemical and biological balance of the normal flora. Recent research is exploring the link between sexual partner treatment and eradication of recurrent cases of BV. Pregnant women and women with sexually transmitted infections are especially at risk for getting this infection. Bacterial vaginosis may sometimes affect women after menopause. A 2005 study by researchers at Ghent University in Belgium showed that subclinical iron deficiency (anemia) was a strong predictor of bacterial vaginosis in pregnant women.[11] A longitudinal study published in February 2006 in the American Journal of Obstetrics and Gynecology showed a link between psychosocial stress and bacterial vaginosis independent of other risk factors.[12][clarification needed]


To make a diagnosis of bacterial vaginosis, a swab from inside the vagina should be obtained. These swabs should be tested for:

Two positive results in addition to the discharge itself are enough to diagnose BV. If there is no discharge, then all three criteria are needed.[13][non-primary source needed] Differential diagnosis for bacterial vaginosis includes the following:[citation needed]

In clinical practice

In clinical practice BV is diagnosed using the Amsel criteria:[13]

  1. Thin, white, yellow, homogeneous discharge
  2. Clue cells on microscopy
  3. pH of vaginal fluid >4.5
  4. Release of a fishy odor on adding alkali—10% potassium hydroxide (KOH) solution.

At least three of the four criteria should be present for a confirmed diagnosis.[3]

Gram stain

An alternative is to use a Gram-stained vaginal smear, with the Hay/Ison[14] criteria or the Nugent[15] criteria. The Hay/Ison criteria are defined as follows:[3]

What this technique loses in interobserver reliability, it makes up in ease and speed of use.

The standards for research are the Nugent[15] Criteria. In this scale, a score of 0-10 is generated from combining three other scores. This method is time consuming and requires trained staff, but it has high interobserver reliability.[citation needed] The scores are as follows:

At least 10–20 high power (1000× oil immersion) fields are counted and an average determined.

Lactobacillus morphotypes — average per high powered (1000× oil immersion) field. View multiple fields.

Gardnerella / Bacteroides morphotypes — average per high powered (1000× oil immersion) field. View multiple fields.

Curved Gram variable rods — average per high powered (1000× oil immersion) field. View multiple fields (note that this factor is less important — scores of only 0–2 are possible)

  • Score 0 for >30
  • Score 1 for 15–30
  • Score 2 for 14
  • Score 3 for <1 (this is an average, so results can be >0, yet <1)
  • Score 4 for 0
  • Score 0 for 0
  • Score 1 for <1 (this is an average, so results can be >0, yet <1)
  • Score 2 for 1–4
  • Score 3 for 5–30
  • Score 4 for >30
  • Score 0 for 0
  • Score 1 for <5
  • Score 2 for 5+

A recent study [16] compared the Gram stain using the Nugent criteria and the DNA hybridization test Affirm VPIII in diagnosing BV. The Affirm VPIII test detected Gardnerella in 107 (93.0%) of 115 vaginal specimens positive for BV diagnosed by Gram stain. The Affirm VPIII test has a sensitivity of 87.7% and specificity of 96% and may be used for the rapid diagnosis of BV in symptomatic women.



Metronidazole or clindamycin either orally or vaginally are effective treatment.[17] However, there is a high rate of recurrence.[9]

The usual medical regimen for treatment is the antibiotic Metronidazole (500 mg twice a day, once every 12 hours) for 7 days.[18] A one-time 2g dose is no longer recommended by the CDC because of low efficacy. Extended release metronidazole is an alternative recommendation.

In contrast to some other infectious diseases affecting the female genitals, according to some sources, treatment of the sexual partners is not necessarily recommended.[19]

Alternative medicine

In 2009 one Cochrane review did not find probiotics useful in the treatment of BV[20] while another concluded they were effective when combined with antibiotics.[17]


Although previously considered a mere nuisance infection, untreated bacterial vaginosis may cause complications, such as increased susceptibility to sexually transmitted infections including HIV, and presents other complications for pregnant women.[21]


It is estimated that 1 in 3 women will develop the condition at some point in their lives.[22]


  1. ^ "Vaginal Infections — How to Diagnose and Treat Them: Bacterial Vaginosis or Vaginal Bacteriosis". Medscape. Retrieved 10 October 2009.
  2. ^ "Bacterial Vaginosis – CDC Fact Sheet". Centers for Disease Control and Prevention. 1 September 2010. Retrieved 11 November 2011.
  3. ^ a b c "National guideline for the management of bacterial vaginosis (2006)". Clinical Effectieness Group, British Association for Sexual Health and HIV (BASHH).
  4. ^ Terri Warren, RN (2010). "Is It a Yeast Infection?". Retrieved 23 February 2011.
  5. ^ Ferris DG, Nyirjesy P, Sobel JD, Soper D, Pavletic A, Litaker MS (March 2002). "Over-the-counter antifungal drug misuse associated with patient-diagnosed vulvovaginal candidiasis". Obstetrics and Gynecology 99 (3): 419–425. doi:10.1016/S0029-7844(01)01759-8. PMID 11864668.
  6. ^
  7. ^ Schwebke, Jane R. (2000). "Asymptomatic bacterial vaginosis". American Journal of Obstetrics & Gynecology 183 (6): 1434–1439. doi:10.1067/mob.2000.107735.
  8. ^ Forney, LJ, Foster, JA, Ledger, W (2006). "The vaginal flora of healthy women is not always dominated by Lactobacillus species". Journal of Infections Diseases 194 (10): 1468–9. PMID 17054080.
  9. ^ a b Bradshaw CS, Morton AN, Hocking J et al. (2006). "High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence". J. Infect. Dis. 193 (11): 1478–86. doi:10.1086/503780. PMID 16652274.
  10. ^
  11. ^ Verstraelen H, Delanghe J, Roelens K, Blot S, Claeys G, Temmerman M (2005). "Subclinical iron deficiency is a strong predictor of bacterial vaginosis in early pregnancy". BMC Infect. Dis. 5: 55. doi:10.1186/1471-2334-5-55. PMC 1199597. PMID 16000177.
  12. ^ Nansel TR, Riggs MA, Yu KF, Andrews WW, Schwebke JR, Klebanoff MA (February 2006). "The association of psychosocial stress and bacterial vaginosis in a longitudinal cohort". Am. J. Obstet. Gynecol. 194 (2): 381–6. doi:10.1016/j.ajog.2005.07.047. PMC 2367104. PMID 16458633.
  13. ^ a b Amsel R, Totten PA, Spiegel CA, Chen KC, Eschenbach D, Holmes KK (1983). "Nonspecific vaginitis. Diagnostic criteria and microbial and epidemiologic associations". Am. J. Med. 74 (1): 14–22. doi:10.1016/0002-9343(83)91112-9. PMID 6600371.
  14. ^ Ison, CA; Hay, PE (2002). "Validation of a simplified grading of Gram stained vaginal smears for use in genitourinary medicine clinics". Sex Transm Infect 78 (6): 413–5. doi:10.1136/sti.78.6.413. PMC 1758337. PMID 12473800. //
  15. ^ a b Nugent RP, Krohn MA, Hillier SL (1991). "Reliability of diagnosing bacterial vaginosis is improved by a standardized method of gram stain interpretation". J. Clin. Microbiol. 29 (2): 297–301. PMC 269757. PMID 1706728.
  16. ^ Gazi H, Degerli K, Kurt O et al. (2006). "Use of DNA hybridization test for diagnosing bacterial vaginosis in women with symptoms suggestive of infection". APMIS 114 (11): 784–7. doi:10.1111/j.1600-0463.2006.apm_485.x. PMID 17078859.
  17. ^ a b Oduyebo OO, Anorlu RI, Ogunsola FT (2009). Oduyebo, Oyinlola O. ed. "The effects of antimicrobial therapy on bacterial vaginosis in non-pregnant women". Cochrane Database Syst Rev (3): CD006055. doi:10.1002/14651858.CD006055.pub2. PMID 19588379.
  18. ^
  19. ^ Potter J (November 1999). "Should sexual partners of women with bacterial vaginosis receive treatment?". Br J Gen Pract 49 (448): 913–8. PMC 1313567. PMID 10818662.
  20. ^ Senok AC, Verstraelen H, Temmerman M, Botta GA (2009). Senok, Abiola C. ed. "Probiotics for the treatment of bacterial vaginosis". Cochrane Database Syst Rev (4): CD006289. doi:10.1002/14651858.CD006289.pub2. PMID 19821358.
  21. ^ "STD Facts — Bacterial Vaginosis (BV)". CDC. Archived from the original on 3 December 2007. Retrieved 4 December 2007.
  22. ^ "The Family Planning Association".