Causes

Bacterial vaginosis (BV) is a common cause of abnormal vaginal discharge in women of reproductive age and affects 30% of women globally (1). It is a polymicrobial syndrome (dysbiosis) characterised by a profound change in the vaginal microbiota from a lactobacilli dominant state to one with high diversity and quantities of anaerobic bacteria including Gardnerella vaginalis, Atopobium vaginae, Mobiluncus spp, Prevotella spp, and other BV-associated bacteria (BVAB). This vaginal dysbiosis is accompanied by a rise in vaginal pH, proteolytic enzymes and volatile amines, which produce the malodour commonly associated with BV.

 

Epidemiological and microbiological data supports sexual transmission of BV. There is a strong association between acquisition of BV and sexual behaviours known to be associated with sexually transmitted infections (STIs), including young age of first sex, increased numbers of sex partners, exposure to new sex partners, penile-vaginal sex and lack of condom use (2). BVAB are also present in the urethra and on the penile skin more often in male partners of women with BV than without, suggesting these bacteria may be exchanged during intercourse  (3-6). In women who have sex with women or couples where both people have a vagina, studies show very high concordance for BV within partnerships and an association with a range of sexual activities (7,8). In addition, post treatment recurrence of BV has been associated with exposure to an ongoing sex partner and lack of condom use for penile-vaginal sex (9,10).

A recent randomised controlled trial undertaken at Melbourne Sexual Health Centre (MSHC) of couples in a current male-female relationship has shown that treating male partners with combination oral and topical antibiotics, at the same time their female partner is receiving first-line antibiotic therapy for BV, significantly improves BV cure over 12 weeks (11). Please see sexual partner treatment below.

 

Clinical presentation

  • Vaginal malodour and/or a thin white or greyish vaginal discharge

  • Up to 50% of women may be asymptomatic 

  • BV is more commonly detected with copper intra-uterine device (IUD) use (12-13). The association between hormonal IUD use and BV is unclear. 

  • BV is associated with increased risk of spontaneous abortion, premature labour, chorioamnionitis, postpartum endometritis and pelvic inflammatory disease (PID). An increased risk of PID has been reported following surgical termination of pregnancy (TOP), IUD insertion or other gynaecological instrumentation. Refer to PID treatment guidelines. 

  • BV is associated with a 2-4 fold increased risk of acquiring STIs including chlamydia, gonorrhoea, herpes simplex type 2 and HIV infection, and increases the risk of HIV transmission to male partners. 

Diagnosis

Test Site/specimen Comments
Amsel's criteria Vaginal swab

A diagnosis is made if 3 or 4 of the following criteria are present:

  1. Clinician observed abnormal vaginal discharge, which is thin, white or grey, often adherent, homogeneous appearance
  2. Vaginal pH of ≥4.5
  3. The presence of “clue cells” on a Gram stain or wet preparation of high vaginal secretions
  4. Positive amine (whiff) test – malodour on examination, or with the addition of 10% KOH can be recorded as a positive whiff test
Nugent's criteria Vaginal swab

A score of 7-10 is diagnostic of BV, and 4-6 is classified as intermediate flora

Approximately 50% of women with intermediate flora by the Nugent method will have BV by the Amsel's method

At MSHC we recommend using both Amsel's and Nugent's methods for the diagnosis of BV
Molecular testing Vaginal swab Identification of BV-related bacteria using a molecular test - often referred to as a nucleic acid amplification test (NAAT) or NAA Testing 

Notes on routine screening before invasive upper genital tract procedures 

There is currently insufficient evidence to support the recommendation of routine screening for BV at the time of insertion of an intrauterine device or surgical termination of pregnancy to prevent PID or endometritis in asymptomatic women (14-20). However, where feasible it is reasonable to provide screening for BV and treatment, if detected, prior to the intervention.

Management

Treatment of the index

Treatment is indicated in: 

  • Symptomatic women 

  • Women undergoing an invasive upper genital tract procedure such as termination of pregnancy or insertion of IUD, where feasible, to reduce the risk of PID/endometritis. The benefit of this practice has not been established.

  • Asymptomatic women requesting treatment 

  • Male partner treatment has now been shown to improve BV cure (see sexual partner treatment below)

Condition

Recommended

Comments

Uncomplicated BV in women who are not pregnant

Metronidazole 400mg PO, twice daily for 7 days

OR

Clindamycin 2% intravaginal cream 5g, nightly for 7 nights (not on PBS)

OR

Metronidazole gel 0.75%, one applicator (5g) intravaginally, nightly for 5 nights (not on PBS)

Metronidazole can cause nausea. Patients should be advised to have their medication with food and to avoid drinking alcohol whilst on treatment and for 48 hours after completion. 

Women should avoid sexual contact or are recommended to use condoms consistently during treatment. However, intravaginal cream or gel may weaken latex condoms.

Partner treatment can now be offered to women with male partners (see below).

Douching and intravaginal cleaning practices have been associated with a non-optimal vaginal microbiota and should be avoided. 

Alternative management for uncomplicated BV in women who are not pregnant

Clindamycin 300mg PO, twice daily for 7 days

OR

Metronidazole 2g, PO, stat*

 

There is currently insufficient evidence to recommend the use of intravaginal lactic acid or vaginal probiotics, however research efforts to determine the role of non-antibiotic or adjunctive regimens in BV treatment are ongoing. Studies have demonstrated improvements in clinical outcomes following the use of a specific Lactobacillus-containing probiotic that is yet to come on the market (21-24).

Pregnant woman

The same treatment options for non-pregnant women can be used in pregnancy

Treatment is recommended in symptomatic pregnant women to alleviate symptoms.

Two meta-analyses of observational studies reported no significant association between metronidazole exposure and congenital malformations (25). Metronidazole is category B2 but a meta-analysis has not demonstrated an association with teratogenic or mutagenic effects in neonates.

Clindamycin is category A. Oral therapy has not been shown to be superior to topical vaginal therapy in pregnancy (26). Therefore, both the oral and topical regimens recommended in non-pregnant women can be used.

Partner treatment can now be offered to women with male partners (see below).

Recurrent BV

Intravaginal metronidazole 0.75% gel 5g twice per week for 4 months (27)

OR

Intravaginal boric acid (seek specialist advice)

BV recurrence is common with >50% of women experiencing post-treatment recurrence within 3-12 months. There are limited data available to guide treatment for highly recurrent BV, although data now suggest that reinfection from partners is likely to contribute to these high rates of recurrence. Partner treatment should be offered to individuals in ongoing relationships (see below).

Intravaginal boric acid regimens have also been used but have not shown sustained benefit. Boric acid can be accessed via compounding pharmacies. Seek specialist advice if required.

* stat treatments are associated with higher recurrence rates of BV (28)

Notes on BV management for IUD users 

Due to the increased risk of BV acquisition and recurrence associated with copper IUD usage: 

  • If a patient using an IUD develops BV treat as recommended above AND

  • If the patient experiences recurrent BV with a copper IUD consider switching to an alternative method or removal and re-treatment prior to re-insertion (29) 

Treatment of sexual partners

A recent randomised controlled trial that treated males with oral metronidazole and topical clindamycin cream twice daily for 7 days, at the same time the female partner received recommended therapy, significantly improved BV cure to 12 weeks (11).

Following the successful outcome of this RCT, MSHC will be transitioning to offering concurrent partner treatment to male-female couples in ongoing relationships. Detailed information on the evidence for male partner treatment including the findings of the trial are available on our website. Specific information is available on this site for clinicians, for pharmacists and for consumers. Resources for clinical use and health education have been developed in parallel with feedback from partner treatment study participants. Further information on consumer experiences will be available soon.  

Condition

Recommended

Comments

Male partner treatment

Metronidazole 400mg PO, twice daily for 7 days

AND

Clindamycin 2% topical cream, applied to the penile skin twice daily for 7 days (not on PBS)

Couples should be advised to synchronise treatment where possible, and abstain from all sexual contact until both partners have completed treatment. If engaging in any sexual activity, use of barrier methods (condoms) is strongly recommended, however clindamycin cream can weaken latex for 72 hours after last dose.

Please provide the medication instructions and the pharmacy letter with the script.

The abbreviated example of partner treatment instructions can be used in your prescription:  

Oral metronidazole: Take one 400mg tablet twice daily for 7 days. Take with food.  

Dalacin – V Cream 2% (2% clindamycin phosphate vaginal cream): Squeeze a line of cream from the tip of your index finger to the first crease. Retract foreskin, if uncircumcised, and rub the cream over the penile head and into the groove below the head. Squeeze a 2nd line of cream onto your finger. Rub it over the full length of the penile shaft, front and back and down to the base of the penis. Repeat this twice daily for 7 days while taking the oral metronidazole tablets. 

 

PT4BV Cream on finger

Image description: A line of cream measured from the fingertip to the first crease 

No trials of partner treatment for couples where both have a vagina have been conducted to inform female partner treatment. However, high concordance for BV is consistently reported within female-female partnerships. Testing of female partners should be offered in order to detect and treat BV in the partner. Where feasible, the alignment of treatment dates may reduce the risk of reinfection.  

MSHC is currently conducting a clinical trial of partner treatment in LGBTQIA+ couples to determine if partner treatment also improves BV cure in this community. 

 

Notes on treating multiple partners 

Couples with additional partners may derive less benefit due to potential reintroduction of BV-associated bacteria from untreated individuals. Where appropriate, consider treating all sexual partners simultaneously to reduce the risk of reinfection. 

References

  1. High Global Burden and Costs of Bacterial Vaginosis: A Systematic Review and Meta-Analysis. Peebles K, Velloza J, Balkus JE, McClelland RS, Barnabas RV. Sex Transm Dis. 2019 May;46(5):304-311
  2. Early sexual experiences and risk factors for bacterial vaginosis. Fethers KA, Fairley CK, Morton A, Hocking JS, Hopkins C, Kennedy LJ, Fehler G, Bradshaw CS. J Infect Dis. 2009 Dec 1;200(11):1662-70
  3. Bacterial communities of the coronal sulcus and distal urethra of adolescent males. Nelson DE, Dong Q, Van der Pol B, Toh E, Fan B, Katz BP, Mi D, Rong R, Weinstock GM, Sodergren E, Fortenberry JD. PLoS One. 2012;7(5):e3629
  4. The Microbiome Composition of a Man's Penis Predicts Incident Bacterial Vaginosis in His Female Sex Partner With High Accuracy. Mehta SD, Zhao D, Green SJ, Agingu W, Otieno F, Bhaumik R, Bhaumik D, Bailey RC. Front Cell Infect Microbiol. 2020 Aug 4;10:43
  5. Bacterial communities in penile skin, male urethra, and vaginas of heterosexual couples with and without bacterial vaginosis. Zozaya M, Ferris MJ, Siren JD, Lillis R, Myers L, Nsuami MJ, Eren AM, Brown J, Taylor CM, Martin DH. Microbiome. 2016 Apr 19;4:1
  6. Penile Microbiota and Female Partner Bacterial Vaginosis in Rakai, Uganda. Liu CM, Hungate BA, Tobian AA, Ravel J, Prodger JL, Serwadda D, Kigozi G, Galiwango RM, Nalugoda F, Keim P, Wawer MJ, Price LB, Gray RH. mBio. 2015 Jun 16;6(3):e00589
  7. The influence of behaviors and relationships on the vaginal microbiota of women and their female partners: the WOW Health Study. Bradshaw CS, Walker SM, Vodstrcil LA, Bilardi JE, Law M, Hocking JS, Fethers KA, Fehler G, Petersen S, Tabrizi SN, Chen MY, Garland SM, Fairley CK. J Infect Dis. 2014 May 15;209(10):1562-72.
  8. Incubation period and risk factors support sexual transmission of bacterial vaginosis in women who have sex with women. Muzny CA, Lensing SY, Aaron KJ, Schwebke JR. Sex Transm Infect. 2019 Nov;95(7):511-515
  9. High recurrence rates of bacterial vaginosis over the course of 12 months after oral metronidazole therapy and factors associated with recurrence. Bradshaw CS, Morton AN, Hocking J, Garland SM, Morris MB, Moss LM, Horvath LB, Kuzevska I, Fairley CK. J Infect Dis. 2006 Jun 1;193(11):1478-8
  10. Recurrence of bacterial vaginosis is significantly associated with posttreatment sexual activities and hormonal contraceptive use. Bradshaw CS, Vodstrcil LA, Hocking JS, Law M, Pirotta M, Garland SM, De Guingand D, Morton AN, Fairley CK. Clin Infect Dis. 2013 Mar;56(6):777-8

  11. Male Partner-Treatment to Prevent Recurrence of Bacterial Vaginosis. Vodstrcil LA, Plummer EL, Fairley CK, Hocking JS, Law MG, Petoumenos K, Bateson D, Murray GL, Donovan B, Chow EPF, Chen MY, Kaldor J, Bradshaw CS. NEJM. 2025 March 6;392(10)

  12. Elevated Risk of Bacterial Vaginosis among Users of the Copper Intrauterine Device: A Prospective Longitudinal Cohort Study. Peebles K, Kiweewa FM, Palanee-Phillips T, Chappell C, Singh D, Bunge KE, Naidoo L, Makanani B, Jeenarain N, Reynolds D, Hillier SL, Brown ER, Baeten JM, Balkus JE; , MTN-020/ASPIRE study team. Clin Infect Dis. 2020 Jun 6
  13. Impact of contraceptive initiation on vaginal microbiota. Achilles SL, Austin MN, Meyn LA, Mhlanga F, Chirenje ZM, Hillier SL. Am J Obstet Gynecol. 2018 Jun;218(6):622.e1-622
  14. Incidence of PID after first trimester legal abortion I women with bacterial vaginosis after treatment with metronidazole: a double blind randomised study. Larsson PG, Platz-Christensen JJ, Thejls H, Forsum U, Påhlson C. Am J Obstet Gynecol 1992; 166: 100-103
  15. Treatment with 2% clindamycin vaginal cream prior to first trimester surgical abortion to reduce signs of postoperative infection: a prospective, double-blinded placebo controlled multicentre study. Larsson PG, Platz-Christensen JJ, Dalaker K, Eriksson K, Fåhraeus L, Irminger K, Jerve F, Stray-Pedersen B, Wølner-Hanssen PÅ. Acta Obstet Scan 2000 May; 79 (5):390-96
  16. Antibiotic prophylaxis to prevent post-abortal upper genital tract infection in women with bacterial vaginosis: randomised controlled trial. Crowley T, Low N, Turner A, Harvey I, Bidgood K, Horner P. BJOG 2001 April; 108(4):396-402
  17. World Health Organization: Medical eligibility criteria for contraceptive use. Geneva: WHO; 2009
  18. FFPRHC Guidance (January 2004): The copper intrauterine device as long-term contraception. Penney G, Brechin S, de Souza A, Bankowska U, Belfield T, Gormley M, Olliver M, Hampton N, Howlett-Shipley R, Hughes S, Mack N. Faculty of Family Planning and Reproductive Health Care Clinical Effectiveness Unit. J Fam Plann Reprod Health Care 2004;30:29–42. 32
  19. FFPRHC Guidance (April 2004): The levonorgestrel-releasing intrauterine system (LNG-IUS) in contraception and reproductive health. J Fam Plann Reprod Health Care 2004;30:99–109
  20. Best practices to minimize risk of infection with intrauterine device insertion. Caddy S, Yudin MH, Hakim J, Money DM. J Obstet Gynaecol Can. 2014 Mar;36(3):266-27
  21. Randomized Trial of Lactin-V to Prevent Recurrence of Bacterial Vaginosis. Cohen CR, Wierzbicki MR, French AL, Morris S, Newmann S, Reno H, Green L, Miller S, Powell J, Parks T, Hemmerling A.N. Engl J Med. 2020 May 14;382(20):1906-1915
  22. VagiBIOM Lactobacillus suppository improves vaginal health index in perimenopausal women with bacterial vaginosis: a randomized control trial. Vivekanandan V, Khan ZH, Venugopal G, Musunuru B, Mishra P, Srivastava S, Ramadass B, Subhadra B. Sci Rep 2024 Feb 9;14(1):3317.
  23. Efficacy and safety of Med-01 probiotics on vaginal health: a 12-week, multicenter, randomized, double-blind, placebo-controlled clinical trial. Park SH, Lee ES, Park ST, Jeong SY, Yun Y, Kim Y, Jeong Y, Kang CH, Choi HJ. Nutrients. 2023 Jan 9;15(2):331.
  24. Impact of Lactobacillus crispatus-containing oral and vaginal probiotics on vaginal health: a randomised double-blind placebo controlled clinical trial. Mändar R, Sõerunurk G, Štšepetova J, Smidt I, Rööp T, Kõljalg S, Saare M, Ausmees K, Le DD, Jaagura M, Piiskop S. Benef Microbes 2023 Apr 18;14(2):143-52.
  25. Screening for Bacterial Vaginosis in Pregnant Adolescents and Women to Prevent Preterm Delivery: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force. Kahwati LC, Clark R, Berkman N, Urrutia R, Patel SV, Zeng J, Viswanathan M. JAMA. 2020 Apr 7;323(13):1293-1309
  26. Early clindamycin for bacterial vaginosis in pregnancy (PREMEVA): a multicentre, double-blind, randomised controlled trial. Subtil D, Brabant G, Tilloy E, Devos P, Canis F, Fruchart A, Bissinger MC, Dugimont JC, Nolf C, Hacot C, Gautier S. Lancet. 2018 Nov 17;392(10160):2171-2179
  27. Suppressive antibacterial therapy with 0.75% metronidazole vaginal gel to prevent recurrent bacterial vaginosis. Sobel JD, Ferris D, Schwebke J, Nyirjesy P, Wiesenfeld HC, Peipert J, Soper D, Ohmit SE, Hillier SL. Am J Obstet Gynecol 2006 May; 194 (5): 1283-
  28. Indications for therapy and treatment recommendations for bacterial vaginosis in non pregnant and pregnant women. Koumans EH, Markowitz LE, Hogan V, CDC BV working group. Clin Infect Dis 2002 Oct 15;35(Supplement_2):S152-72.
  29. FSRH Clinical Guideline: Intrauterine Contraception (April 2015, amended September 2019) 

Disclaimer

We recognise that gender identity is fluid. In our treatment guidelines, the words and language we use to describe genitals and gender are based on the sex assigned at birth.

The content of these treatment guidelines is for information purposes only. The treatment guidelines are generic in character and should be applied to individuals only as deemed appropriate by the treating practitioner on a case by case basis. Alfred Health, through MSHC, does not accept liability to any person for the information or advice (or the use of such information or advice) which is provided through these treatment guidelines. 

The information contained within these treatment guidelines is provided on the basis that all persons accessing the treatment guidelines undertake responsibility for assessing the relevance and accuracy of the content and its suitability for a particular patient. Responsible use of these guidelines requires that the prescriber is familiar with contraindications and precautions relevant to the various pharmaceutical agents recommended herein.