|Classification and external resources|
Bacterial vaginosis (BV) or very uncommonly vaginal bacteriosis 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. 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.
Signs and symptoms
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. 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, though others argue that this is often a misdiagnosis.
A healthy vagina normally contains many microorganisms; some of the most common ones are Lactobacillus species, including L. crispatus, L. gasseri, L. jensenii, and L. iners. 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, and include Gardnerella vaginalis, Mycoplasma hominis, Ureaplasma urealyticum, and species of the genera Peptostreptococcus and Mobiluncus, as well as anaerobic Gram-negative rod-shaped species such as Prevotella and Bacteroides. 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.
One of the most direct causes of BV is douching, which alters the vaginal flora and predisposes women to developing BV. Douching is strongly discouraged by the U.S. Department of Health and Human Services and various medical authorities, for this and other reasons.
Although BV can be associated with sexual activity, there is no clear evidence of sexual transmission. 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. A longitudinal study published in February 2006 in the American Journal of Obstetrics and Gynecology showed a link between psychosocial stress and bacterial vaginosis persisted even when other risk factors were accounted for.
To make a diagnosis of bacterial vaginosis, a swab from inside the vagina should be obtained. These swabs should be tested for:
- A characteristic "fishy" odor on wet mount. This test, called the whiff test, is performed by adding a small amount of potassium hydroxide to a microscopic slide containing the vaginal discharge. A characteristic fishy odor is considered a positive whiff test and is suggestive of bacterial vaginosis.
- Loss of acidity. To control bacterial growth, the vagina is normally slightly acidic with a pH of 3.8–4.2. A swab of the discharge is put onto litmus paper to check its acidity. A pH greater than 4.5 is considered alkaline and is suggestive of bacterial vaginosis.
- The presence of clue cells on wet mount. Similar to the whiff test, the test for clue cells is performed by placing a drop of sodium chloride solution on a slide containing vaginal discharge. If present, clue cells can be visualized under a microscope. They are so-named because they give a clue to the reason behind the discharge. These are epithelial cells that are coated with bacteria.
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.[non-primary source needed] Differential diagnosis for bacterial vaginosis includes the following:
- Normal discharge.
- Candidiasis (thrush, or a yeast infection).
- Trichomoniasis, an infection caused by Trichomonas vaginalis.
In clinical practice
In clinical practice BV can be diagnosed using the Amsel criteria:
- Thin, white, yellow, homogeneous discharge
- Clue cells on microscopy
- pH of vaginal fluid >4.5
- 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. The modified Amsel Criteria is equally diagnostic of BV as the Amsel's. The modified Amsel Criteria says two instead of the three out of the four criteria is diagnostic of BV.
BV can also be diagnosed with BVBLUE, a CLIA-waived rapid diagnostic that tests for sialidase enzyme activity. Studies have shown this test to be more accurate, specific, and comprehensive than the Amsel criteria.
- Grade 1 (Normal): Lactobacillus morphotypes predominate.
- Grade 2 (Intermediate): Mixed flora with some Lactobacilli present, but Gardnerella or Mobiluncus morphotypes also present.
- Grade 3 (Bacterial Vaginosis): Predominantly Gardnerella and/or Mobiluncus morphotypes. Few or absent Lactobacilli. (Hay et al., 1994)
NB: Gardnerella vaginalis is the main culprit in BV. Gardnerella vaginalis is a short rod, therefore, it is a coccobacillus. The bacteria that have covered the squamous epithelial cells making the epithelial cells have obsured ends are not bacilli, they are coccobacilli. Hence, the presence of clue cells and gram variable coccobacilli are indicative or diagnostic of Bacterial Vaginosis.
The standards for research are the Nugent 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. The scores are as follows:
- 0–3 is considered negative for BV
- 4–6 is considered intermediate
- 7+ is considered indicative of BV.
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.
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)
A recent study  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. However Affirm VPIII does have some drawbacks: 1) It requires a very expensive proprietary piece of equipment to read results, and 2) it does not detect other pathogens that cause BV, including Prevotella spp, Bacteroides spp, & Mobiluncus spp.
Metronidazole or clindamycin either orally or vaginally are effective treatment. However, there is a high rate of recurrence. Recurrence rates are increased with sexual activity with the same pre-/posttreatment partner and inconsistent condom use although estrogen-containing contraceptives decrease recurrence 
The usual medical regimen for treatment is the antibiotic Metronidazole (500 mg twice a day, once every 12 hours) for 7 days. A one-time 2g dose is no longer recommended by the CDC because of low efficacy. Extended release metronidazole is an alternative recommendation.
Alternatively, antibiotics may be applied topically (vaginally).
Several studies have found probiotics (containing Lactobacillus bacteria species, including L. rhamnosus, L. reuteri, L. acidophilus, and L. fermentum) to be highly effective (88–90% cure rate at 1 month) either alone or in combination with antibiotics, either taken orally or applied topically (vaginally), and significantly superior to antibiotics alone.
Some studies have also found probiotics useful in maintenance therapy, preventing recurrence. One Italian study found that once-weekly application of probiotics for 6 months almost completely prevented recurrence at 6 months (96%), and was still effective at 12 months.
The term prebiotic is used for a nutrient that stimulates the healthy vaginal micro-flora. The term is generally used for food components that improve human health by selectively stimulating the growth and/or activity of existing bacteria in the intestine  The concept of prebiotics assumes that the imbalance in vaginal micro-flora is influenced by a depletion of nutrient and substrate needed for the lactobacilli to multiply and produce lactic acid. The natural substrate for acid production is glycogen, which is deposited in epithelial cells. Lactose is the preferred compound, as it is generally fermented by lactobacilli, and it is not assimilated by Gardnerella vaginalis and Candida spp. (C. albicans, C. glabrata, C. krusei)., The beneficial effect on several vaginal nuisances was indicated by a user survey. The clinical trial is still pending, but the concept was proven by a Chinese study using sucrose 
One study in 2007 focused on the occurrence of BV and a person's dietary intake. Research showed that ingestion of folate, calcium and vitamin E has an inverse effect on severe BV (increased ingestion of these nutrients decreases the risk of BV). The conclusions in the same study suggests that fat intake was a predictor for acquiring BV. Women who had higher ratios of fats had the risk for severe BV increase twofold.
Although previously considered a mere nuisance infection, untreated bacterial vaginosis may cause complications, such as increased susceptibility to sexually transmitted infections including HIV and pregnancy complications.
It has been shown that HIV-infected women with bacterial vaginosis (BV) have higher HIV concentrations in their vaginal secretions. Diagnostic criteria for BV have also been associated with a female genital tract factor that induces expression of HIV. The elevated HIV copy number in vaginal secretions of women with BV has been associated with an increased risk of heterosexual transmission of HIV.
Also, clinical studies have shown that BV-associated bacterial microbiota can activate HIV replication leading to significant increase in HIV production in the female genital tract, as detected in the vaginal secretions. Moreover, bacterial extracts of the leading causes of BV (i.e. Gardenella vaginalis and some vaginal anareobic bacteria) may increase HIV production. Extracts from these bacterial cultures increased HIV production by more than 100 fold, as measured by HIV antigen (p24) production. Interestingly, pathogenic strains of G vaginalis were shown to be stronger inducers of HIV production, than the less pathogenic G vaginalis strains, which have weaker association with BV.
It is estimated that 1 in 3 women will develop the condition at some point in their lives.
- "Vaginal Infections — How to Diagnose and Treat Them: Bacterial Vaginosis or Vaginal Bacteriosis". Medscape. Retrieved 10 October 2009.
- "Bacterial Vaginosis – CDC Fact Sheet". Centers for Disease Control and Prevention. 1 September 2010. Retrieved 11 November 2011.
- "National guideline for the management of bacterial vaginosis (2006)". Clinical Effectieness Group, British Association for Sexual Health and HIV (BASHH).
- Terri Warren, RN (2010). "Is It a Yeast Infection?". Retrieved 23 February 2011.
- 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.
- Schwebke, Jane R. (2000). "Asymptomatic bacterial vaginosis". American Journal of Obstetrics & Gynecology 183 (6): 1434–1439. doi:10.1067/mob.2000.107735.
- 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. doi:10.1086/508497. PMID 17054080.
- Cottrell, B. H. (2010). "An Updated Review of of Evidence to Discourage Douching". MCN, the American Journal of Maternal/Child Nursing 35 (2): 102–107; quiz 107–9. doi:10.1097/NMC.0b013e3181cae9da. PMID 20215951.
- Velasquez-Manoff, Moises (Jan 11, 2013). "What’s in Your Vagina? A healthy microbiome, hopefully.". Slate.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Oduyebo OO, Anorlu RI, Ogunsola FT (2009). "The effects of antimicrobial therapy on bacterial vaginosis in non-pregnant women". In Oduyebo, Oyinlola O. Cochrane Database Syst Rev (3): CD006055. doi:10.1002/14651858.CD006055.pub2. PMID 19588379.
- Bradshaw, CS; Vodstrcil, LA; Hocking, JS; Law, M; Pirotta, M; Garland, SM; De Guingand, D; Morton, AN; Fairley, CK (Mar 2013). "Recurrence of bacterial vaginosis is significantly associated with posttreatment sexual activities and hormonal contraceptive use.". Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 56 (6): 777–86. doi:10.1093/cid/cis1030. PMID 23243173.
- Diseases Characterized by Vaginal Discharge, from Centers for Disease Control and Prevention. Page last updated: April 12, 2007
- Mehta SD (October 2012). "Systematic review of randomized trials of treatment of male sexual partners for improved bacteria vaginosis outcomes in women". Sex Transm Dis 39 (10): 822–30. doi:10.1097/OLQ.0b013e3182631d89. PMID 23007709.
- 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.
- Senok AC, Verstraelen H, Temmerman M, Botta GA (2009). "Probiotics for the treatment of bacterial vaginosis". In Senok, Abiola C. Cochrane Database Syst Rev (4): CD006289. doi:10.1002/14651858.CD006289.pub2. PMID 19821358.
- Anukam, K.; Osazuwa, E.; Ahonkhai, I.; Ngwu, M.; Osemene, G.; Bruce, A. W.; Reid, G. (2006). "Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: Randomized, double-blind, placebo controlled trial". Microbes and Infection 8 (6): 1450–1454. doi:10.1016/j.micinf.2006.01.003. PMID 16697231.
- Anukam, K. C.; Osazuwa, E.; Osemene, G. I.; Ehigiagbe, F.; Bruce, A. W.; Reid, G. (2006). "Clinical study comparing probiotic Lactobacillus GR-1 and RC-14 with metronidazole vaginal gel to treat symptomatic bacterial vaginosis". Microbes and Infection 8 (12–13): 2772–2776. doi:10.1016/j.micinf.2006.08.008. PMID 17045832.
- Marcone, V.; Rocca, G.; Lichtner, M.; Calzolari, E. (2010). "Long-term vaginal administration of Lactobacillus rhamnosus as a complementary approach to management of bacterial vaginosis". International Journal of Gynecology & Obstetrics 110 (3): 223–226. doi:10.1016/j.ijgo.2010.04.025. PMID 20573348.
- Gibson GR, Roberfroid MB. Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr. 1995;125(6):1401-12
- Boskey ER, Telsch KM, Whaley KJ, Moench TR, Cone RA: Acid production by vaginal flora in vitro is consistent with the rate and extent of vaginal acidification. Infect Immun. 1999 Oct;67(10):5170-5
- John Holt et al.(ed): Bergey's manual of determinative bacteriology, 9th ed. (1994) ISBN 978-0-683-00603-2. Williams & Wilkins, Baltimore, USA p. 199
- Human RP & Tillotson: Identification of Gardnerella vaginalis with the API 20 STREP system. J. Clin. Microbiol. 21(6)985–986
- Meyer SA, Ahern DG & Yarrow D: Genus 4. Candida Berkhout. Ch.apter in Kreger-Van Rij, NJW. (ed) 1984 . The Yeasts a taxonomic study. 3rd Ed. Elsevier Sci.Pub. B.V., Amsterdam, The Netherlands. p 612, 687, 727
- Emery SJ; Tomlinson MJ; Hansen, ID: Patient-reported effects of vaginal lactose as a prebiotic for bacterial vaginosis, doi:10.1136/sextrans-2012-050601c.51
- Zeng ZM, Liao QP, Yao C, Geng L, Feng LH, Shi HR, Xin XY, Li P, Wang HL, Pang YC, Liu SW, Jiang SB (2010): Directed shift of vaginal flora after topical application of sucrose gel in a phase III clinical trial: a novel treatment for bacterial vaginosis.Chin Med J (Engl). 2010 Aug 5;123(15):2051-
- Neggers Y, Tonja R, Andrews W, Schwebke J, Kai-fun Y (September 2007). "Dietary Intake of Selected Nutrients Affects Bacterial Vaginosis in Women". Journal of Nutrition 137 (09): 2128–2133. PMC 2663425. PMID 17709453.
- "STD Facts — Bacterial Vaginosis (BV)". CDC. Archived from the original on 3 December 2007. Retrieved 4 December 2007.
- J Acquir Immune Defic Syndr. 2005 Jul 1;39(3):340-6.
- AIDS. 1999 Oct 1;13(14):1905-12.
- PLoS Med. 2012;9(6):e1001251. doi: 10.1371/journal.pmed.1001251. Epub 2012 Jun 26.
- J Acquir Immune Defic Syndr. 1999 Jul 1;21(3):194-202.
- J Infect Dis. 1999 Apr;179(4):924-30.
- J Infect Dis. 2000 May;181(5):1574-80. Epub 2000 May 15.
- J Infect Dis. 2001 Jul 1;184(1):22-7. Epub 2001 May 22.
- Bacterial vaginosis from National Health Service, UK. Page last reviewed: 03/10/2013
- "The Family Planning Association".