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Bacterial Vaginosis

Basics

Description

- Proliferation of the following organisms in the vaginal milieu: - Gardnerella vaginalis, most commonly - Mycoplasma hominis - Anaerobes such as Mobiluncus, Bacteroides, and Peptostreptococcus species

- Increases susceptibility to HIV and other sexually transmitted infections (STIs) - Complications in pregnancy - Preterm labor and delivery - Premature rupture of membranes - Spontaneous abortion

- Vaginal douching or heavy soap use - Signs and symptoms: - Thin, white, homogenous discharge - Malodorous, "fishy"¯ discharge - Dyspareunia, dysuria rare

- pH >4.5 (normal = 4.5) - Light microscopy (see below) - 10% KOH preparation for Whiff test - Small amount of vaginal discharge is placed on glass slide - A drop of KOH is added to slide - Production of an amine (or "fishy"¯) odor indicates a positive Whiff test

- Gram stain - Often considered the gold standard (1)[A] - Presence of small gram-negative rods or gram-variable rods and the absence of longer lactobacilli is highly predictive of BV - Less convenient for establishing diagnosis in office

- DNA probe (1)[B] - Commercially available probe that simultaneously detects presence of Candida species, G. vaginalis, and Trichomonas vaginalis from single vaginal swab - Results within 45 minutes - Must be performed in the laboratory - Sensitivity 73-89%, specificity 88-97% - Does not detect BV that is caused by organisms other than G. vaginalis

- Colorimetric pH and amine card (1)[C] - Detection of pH >4.7 and presence of vaginal fluid amines - Rapid diagnosis in office setting - Sensitivity, 40-89% and specificity, 61-95%

- Screen for STIs if indicated: - HIV - Chlamydia - Gonorrhea - Trichomoniasis - Syphilis - Hepatitis B and C

- Findings - Presence of clue cells (≥20% of all cells) - Absence of lactobacilli - Scant white blood cells

- Clindamycin - Tablets: 300 mg PO b.i.d. — 7 days - Ovules: 100 g intravaginally qhs — 3 days - Bioadhesive cream 2%: 5 g — 1 dose

- Untreated BV is associated with higher risks of the following: - Transmission of HIV and other STIs - Complications in patients undergoing gynecologic procedures or surgeries - Vaginal cuff cellulitis - Pelvic inflammatory disease - Endometritis

- Recurrence - Occurs in approximately 30% within first 3 months after treatment - Unclear if recurrence occurs secondary to: - Failure to restore balance of normal flora because of organisms resistant to current antibiotic regimens - Failure to treat an unidentified pathogen - Reinfection from untreated partners - Hygiene practices that disrupt the balance of normal flora - OR a combination of above factors

  • Bacterial vaginosis (BV) is the most common cause of vaginal discharge.Accounts for up to 50% of cases of vaginal discharge in women of childbearing age.
  • Other common causes of vaginal discharge include:Candidal vulvovaginitisTrichomoniasis
  • BV is caused by an imbalance of the normal flora in the vaginal milieu, leading to the presence of vaginal discharge.
  • Vaginitis is inflammation of the vagina resulting in discharge with or without pain.
  • Because of the absence of inflammation in BV, the term "vaginosis"¯ is used instead of "vaginitis."¯

Epidemiology

Prevalence

  • Prevalence of 5-60% worldwide
  • Difficult to estimate exact prevalence as many women are asymptomatic
  • Can occur in heterosexual and lesbian womenHigher prevalence among African American women and women who partner with womenPrevalence among pregnant women in the USA: 10-35%

Risk Factors

  • Vaginal douching
  • New sexual partner
  • Multiple sexual partners
  • Women who have sex with women
  • Tobacco use

General Prevention

  • Avoiding douching
  • Safe sex practices as higher number of sexual partners associated with higher rates of BV

Pathophysiology

  • Caused by imbalance of normal floraDecrease in lactobacilli and proliferation of other organisms, particularly anaerobic gram-negative rods (see "Etiology"¯)
  • Unclear whether initial pathogenic event is overgrowth of anaerobes or decrease in lactobacilli.
  • Role of sexual transmission is controversial.Higher-risk sex practices (higher number of sexual partners) have been associated with higher rates of BV in both heterosexual and lesbian women.However,Treating male partners of women with BV is not beneficial.Women who are not sexually active can develop BV.

Etiology

  • Proliferation of the following organisms in the vaginal milieu:Gardnerella vaginalis, most commonlyMycoplasma hominisAnaerobes such as Mobiluncus, Bacteroides, and Peptostreptococcus species

Associated Conditions

  • Increases susceptibility to HIV and other sexually transmitted infections (STIs)
  • Complications in pregnancyPreterm labor and deliveryPremature rupture of membranesSpontaneous abortion

Diagnosis

  • Diagnosis is made by the presence of 3 of the 4 criteria, known as Amsel's criteria (1)[A] (sensitivity = >90%, specificity = 77%):Thin, white, homogenous dischargeVaginal pH >4.5Positive Whiff test (amine odor when potassium hydroxide [KOH] added)Presence of clue cells on light microscopySquamous cells with irregular borders secondary to studding of bacteria to cell membraneShould account for 20% of cells on wet mountPresence of clue cells is single most reliable predictor of BV

History

  • Vaginal douching or heavy soap use
  • Signs and symptoms:Thin, white, homogenous dischargeMalodorous, "fishy"¯ dischargeDyspareunia, dysuria rare
  • 50-75% of women may be asymptomatic.

Physical Exam

  • Inspection and speculum exam reveals normal vulva, vaginal mucosa, and cervix.
  • Signs of mucosal erythema and irritation are typically absent.
  • Thin, white, homogenous discharge is present in the vaginal vault.

Tests

Lab

  • pH >4.5 (normal = 4.5)
  • Light microscopy (see below)
  • 10% KOH preparation for Whiff testSmall amount of vaginal discharge is placed on glass slideA drop of KOH is added to slideProduction of an amine (or "fishy"¯) odor indicates a positive Whiff test
  • Gram stainOften considered the gold standard (1)[A]Presence of small gram-negative rods or gram-variable rods and the absence of longer lactobacilli is highly predictive of BVLess convenient for establishing diagnosis in office
  • DNA probe (1)[B]Commercially available probe that simultaneously detects presence of Candida species, G. vaginalis, and Trichomonas vaginalis from single vaginal swabResults within 45 minutesMust be performed in the laboratorySensitivity 73-89%, specificity 88-97%Does not detect BV that is caused by organisms other than G. vaginalis
  • Colorimetric pH and amine card (1)[C]Detection of pH >4.7 and presence of vaginal fluid aminesRapid diagnosis in office settingSensitivity, 40-89% and specificity, 61-95%
  • Screen for STIs if indicated:HIVChlamydiaGonorrheaTrichomoniasisSyphilisHepatitis B and C
  • Samples for pH, microscopy, DNA probe, and culture should be obtained from the posterior fornix or vaginal wall.
  • Obtaining a sample from cervical os may reveal normal cervical mucous.

Diagnostic Procedures/Other

  • Light microscopyNormal saline wet preparation slidePlace thin layer of discharge on glass slideAdd 1 drop of normal saline to slideFindingsPresence of clue cells (≥20% of all cells)Absence of lactobacilliScant white blood cells

Differential Diagnosis

  • Atrophic vaginitis
  • Trichomoniasis
  • Candidal vulvovaginitis
  • Desquamative inflammatory vaginitis

Treatment

  • Treatment is recommended for symptomatic women (1)[A].
  • Treatment for asymptomatic women should be considered; however, complications (see "Complications"¯) can occur in patients with untreated BV, particularly in (1)[B]:Pregnant womenWomen undergoing gynecologic procedures and/or surgeriesWomen at risk for STIs

Medication

First Line

  • Metronidazole: 500 mg PO b.i.d. — 7 days (1)[A]
  • Metronidazole gel 0.75%: 5 g intravaginally daily — 5 days
  • Clindamycin 2% cream: 5 g intravaginally qhs — 7 days

Second Line

  • ClindamycinTablets: 300 mg PO b.i.d. — 7 daysOvules: 100 g intravaginally qhs — 3 daysBioadhesive cream 2%: 5 g — 1 dose

Additional Treatment

Issues for Referral

Consider referral to an obstetrician or a gynecologist if no resolution of symptoms after treatment.

Complementary and Alternative Medicine

  • Small studies have demonstrated that lactobacillus suppositories and oral lactobacillus may decrease recurrent BV.Lactobacillus suppositories 1 capsule intravaginally for 7 days — 2 courses, given 7 days apart (2)[C]Oral yogurt with live Lactobacillus acidophilus cultures may reduce episodes of BV (3)[C]
  • Twice daily yogurt douches — 7 days may be an effective treatment in pregnant women (3)[C].

In-Patient Considerations

Treatment is primarily outpatient.

Ongoing Care

Follow-Up Recommendations

Cure rate with first-line medication is >90%; slightly lower with second-line regimens.

Patient Monitoring

Consider screening for STIs

Patient Education

  • Avoid douching or heavy soap use
  • Studies do not demonstrate reduced rates of recurrence in women whose partners were also treated for BV.

Complications

  • Untreated BV is associated with higher risks of the following:Transmission of HIV and other STIsComplications in patients undergoing gynecologic procedures or surgeriesVaginal cuff cellulitisPelvic inflammatory diseaseEndometritisComplications in pregnancy (see "Pregnancy"¯)
  • RecurrenceOccurs in approximately 30% within first 3 months after treatmentUnclear if recurrence occurs secondary to:Failure to restore balance of normal flora because of organisms resistant to current antibiotic regimensFailure to treat an unidentified pathogenReinfection from untreated partnersHygiene practices that disrupt the balance of normal floraOR a combination of above factorsRegimensTreatment with metronidazole 500 mg PO b.i.d. — 10-14 daysConsider suppression with metronidazole 0.75% vaginal gel — 10 days then biweekly — 4-6 monthsConsider adding boric acid 600 mg vaginally — 21 days to oral metronidazole regimen to improve rate of cure
  • In pregnancy, BV has been associated with the following:Preterm deliveryPreterm laborPremature rupture of membranesSpontaneous abortion
  • CDC recommends treatment of symptomatic pregnant women (1)[A].
  • CDC no longer discourages use of oral metronidazole in first trimester as has not been associated with birth defects.Metronidazole 500 mg po b.i.d. or 250 mg t.i.d. — 7 daysClindamycin 300 mg b.i.d. — 7 days
  • Treatment of asymptomatic pregnant women does not improve pregnancy outcomes.Therefore, CDC recommends against routine treatment of asymptomatic pregnant women at average risk for preterm labor.Detection and treatment of BV should therefore ideally occur prior to pregnancy.
  • Pregnant women at high risk for preterm laborHigh risk usually defined as prior preterm delivery.Screening is an option, but the US Preventative Services Task Force (USPSTF) does not recommend for or against routine screening given insufficient evidence (4)[C].
  • Breastfeeding womenWomen should withhold breastfeeding during treatment with metronidazole and for 12-24 hours after last dose to reduce the exposure of infant to metronidazole.Clindamycin 300 mg bid — 7 days is alternative although infant should be monitored for antibiotic-associated colitis.

References

1Workowski KA, Berman S Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep. 2010;59:1-110. [View Abstract]2Ya W, Reifer C, Miller LE Efficacy of vaginal probiotic capsules for recurrent bacterial vaginosis: A double-blind, randomized, placebo-controlled study. Am J Obstet Gynecol. 2010;203:120. [View Abstract]3Van Kessel K, Assefi N, Marrazzo J. Common complementary and alternative therapies for yeast vaginitis and bacterial vaginosis: A systematic review. Obstet Gynecol Surv. 2003;58:351-358. [View Abstract]4 The guide to clinical preventative services 2010-2011. AHRQ Publication No. 10-05145, 2010.

Additional Reading

1Allsworth JE, Peipert JF Prevalence of bacterial vaginosis: 2001-2004 National Health and Nutrition Examination Survey data. Obstet Gynecol. 2007;109:114-120. [View Abstract]2Bradshaw CS, Morton AN, Garland SM. Higher-risk behavioral practices associated with bacterial vaginosis compared with vaginal candidiasis. Obstet Gynecol. 2005;106:105-114. [View Abstract]3Hale TW Drug therapy and breastfeeding: Antibiotics, analgesics, and other medications. NeoReviews. 2005;6(5):e233.4Turovskiy Y, Noll KS, Chikindas ML. The aetiology of bacterial vaginosis. J Appl Microbiol. 2011;110(5):1105-1128. [View Abstract]

Additional Reading see also

Absence of lactobacilli and clue cells: Obliteration of sharp borders of squamous cells secondary to studding of bacteria to cell membrane.

Codes

ICD9

  • 616.10 Vaginitis and vulvovaginitis, unspecified
  • 623.5 Vaginal discharge NOS

ICD10

  • N76.1 Subacute and chronic vaginitis
  • N89.8 Other specified noninflammatory disorders of vagina

SNOMED

  • 419760006 bacterial vaginosis (disorder)
  • 271939006 vaginal discharge (finding)
  • 30800001 vaginitis (disorder)

Clinical Pearls

  • Bacterial vaginosis (BV) is caused by an imbalance of vaginal flora.Overgrowth of Gardnerella vaginalis is most common.
  • Treatment of all symptomatic women is recommended.
  • Treatment of asymptomatic women should be considered as BV is associated with higher transmission rates of HIV, postoperative infections, and complications in pregnancy.
  • Treatment of pregnant women does not decrease risk of preterm labor; therefore, identification and treatment of BV should ideally occur prior to pregnancy.