STI Part 3 – Canadian Guideline

7. Vaginal Discharge (Bacterial Vaginosis, Vulvovaginal Candidiasis, Trichomoniasis)


  • The three infections most commonly associated with vaginal discharge in adult women are:
    1. Bacterial vaginosis (BV) – Not STI
      • Most common cause of vaginal discharge.
      • Characterized by an overgrowth of genital tract organisms (e.g., Gardenerella, Prevotella, Mobiluncus spp.) and a depletion of lactobacilli.
    2. Vulvovaginal candidiasis (VVC) – Not STI
      • ~ 90% of cases caused by Candida albicans; remainder caused by other Candida spp. (e.g., C. glabrata) or Saccharomyces cerevisiae.
    3. Trichomoniasis – STI
      • Caused by Trichomonas vaginalis, a protozoa.
    4. On occasion, vaginal discharge may be seen in cervicitis caused by G&C
  • Non-infectious causes of vaginal discharge include the following:
    • Excessive physiologic secretions
    • Desquamative inflammatory vaginitis
    • Atrophic vaginitis (scant discharge)
    • Foreign bodies
  • Non-infectious causes of vulvovaginal pruritus without discharge should also be considered:
    • Irritant or allergic dermatitis (e.g., latex, soaps, perfumes)
    • Skin disorders, such as the following:
      • Lichen sclerosus (may increase the risk of vulvar cancer)
      • Squamous cell hyperplasia
      • Lichen planus
      • Psoriasis


  • Vaginal complaints are common in primary care and are among the most common reasons for gynecological consultation.
Bacterial vaginosis
  • Prevalence has been estimated at 10–30% of pregnant women and 10% of family practice patients.
  • BV during pregnancy is associated with PROM, chorioamnionitis, preterm labour / birth and post-cesarean delivery endometritis.
  • The presence of BV during an invasive procedure: (IUD) insertion, endometrial biopsy or uterine curettage, has been associated with post-procedure PID and vaginal cuff cellulitis.
  • Presence of BV is associated with increased acquisition of HIV.
Vulvovaginal candidiasis
  • ~ 75% of women exp 1 episode of VVC during their lifetime, and 5–10% > 1 episode.
  • The incidence of recurrent VVC (≥ 4 symptomatic episodes of VVC a year) has been estimated at 5% of women of reproductive age.
  • Among HIV-positive women, lower CD4 counts and high viral loads are associated with persistent Candida colonization and an increased incidence of VVC.
  • the prevalence was estimated to range from 10–35%; Among men attending STI clinics, the prevalence has been estimated at 3–20%.
  • Trichomoniasis is associated with an increased risk of HIV acquisition and transmission in women.

Manifestations and Diagnosis

  • Nonspecific s/sx, Definitive diagnosis is based on laboratory testing

Diagnostic features and laboratory diagnosis

Clue cells are vaginal epithelial cells covered with numerous coccobacilli.
Culture is more sensitive than microscopy for T. vaginalis.
Sexual transmission
  • Not usually considered STI
  • Not usually considered STI
  • STI
Predisposing factors
  • Often absent
  • sexually active
  • New sexual partner
  • IUD use
  • Often absent
  • sexually active
  • Current or recent antibiotic use
  • Pregnancy
  • Corticosteroids
  • Poorly controlled diabetes
  • Immuno-compromised
  • Multiple partners
  • Vaginal discharge
  • Fishy odour
  • 50% asymptomatic
  • Vaginal discharge
  • Itch
  • External dysuria
  • Superficial dyspareunia
  • Up to 20% asymptomatic
  • Vaginal discharge
  • Itch
  • Dysuria
  • 10–50% asymptomatic
  • White or grey, thin, copious discharge
  • White, clumpy, curdy discharge
  • Erythema and edema of vagina and vulva
  • Off-white or yellow, frothy discharge
  • Erythema of vulva and cervix (“strawberry cervix”)
Vaginal pH
  • >4.5
  • <4.5
  • >4.5
Wet mount
  • PMNs
  • Clue cells
  • Budding yeast
  • Pseudohyphae
  • Motile flagellated protozoa (38–82% sensitivity)
Gram stain
  • Clue cells + Decreased normal flora
  • Predominant Gram-negative curved bacilli and coccobacilli
  • PMNs
  • Budding yeast
  • Pseudohyphae
  • PMNs
  • Trichomonads
Whiff test
  • Positive
  • Negative
  • Negative
Preferred treatment
  • Metronidazole
  • Clindamycin
  • Antifungals
  • Metronidazole
  • Treat partner; practice safe sex

Specimen collection

  • Speculum examination.
  • Rule out cervicitis.
  • Collect a sample of the discharge from the vaginal wall for microscopy (if microscopy is not available on-site – syndrome Rx)
  • Although not a sensitive test, Gram stain may be helpful in diagnosing mucopurulent cervicitis (MPC) and gonorrhea in symptomatic females.
  • A negative wet mount does not rule out an infectious cause of vaginitis.
  • Culture is rarely needed in acute cases of vaginitis.
Test Procedure Normal result
While KOH destroys cellular debris and allows one to more clearly detect yeast cells and hyphae, it also destroys the epithelial cells in clue cells needed to diagnose BV and lyses trichomonads. Therefore, for vaginitis, saline is necessary.
pH test
  • Use narrow-range pH paper
pH ≤4.5
Wet mount
  • Place a drop of vaginal discharge on a slide; mix with a drop of 0.9% saline; apply a cover slip; examine immediately under a microscope at low and high power
  • Examine for leukocytes, clue cells, lactobacilli, yeast and trichomonads
Epithelial cells and rare white blood cells
Whiff test/ KOH slide (optional)
  • Place a drop of discharge on a slide; mix with a drop of 10% KOH; an amine (fishy) odour after applying the KOH is a positive test; apply a cover slip; examine under a microscope at low and high power
  • Examine for yeast
Gram stain Predominantly large Gram-positive bacilli

Syndromic management of vaginal discharge

If no on-site microscopy, use the WHO algorithm for management of vaginal discharge.

Figure 1

Consideration for Other STIs

  • In a case of trichomoniasis, other STIs need to be considered. Specimens can be taken for the following:
    • Gonorrhea and chlamydia and Syphilis
    • HIV and Hepatitis B
  • Discuss HPV vaccine with women

Treatment of bacterial vaginosis

Asymptomatic – Treatment is unnecessary except in cases of:
  • High-risk pregnancy (history of preterm delivery)
  • Prior to IUD insertion
  • Prior to gynecologic surgery, therapeutic abortion or upper tract instrumentation
  • Metronidazole 500 mg PO bid for 7 days
  • Metronidazole gel 0.75%, one applicator (5 g) once a day intravaginally for 5 days
  • Clindamycin cream 2%, one applicator (5 g) intravaginally once a day for 7 days


  • Metronidazole 2 g PO in a single dose
  • Clindamycin 300 mg PO bid for 7 days (Clindamycin cream is oil-based and may cause latex condoms or diaphragms to fail)
  • For therapy with metronidazole, a 7 day oral course and a 5 day course of gel are equally efficacious (cure rate 75–85%). A single oral dose also has a cure rate of 85% but a higher relapse rate at 1 month (35–50% vs. 20–33%)
  • In one study, clindamycin cream was equivalent to both metronidazole regimens (cure rate of 75–86%)
Recurrent bacterial vaginosis
  • 15–30% of patients develop a recurrence in the first 1–3 months after treatment and need to Reconfirm diagnosis.
Treatment of recurrent bacterial vaginosis
  • Metronidazole 500 mg PO bid for 10–14 days 
  • Metronidazole gel 0.75%, one applicator (5 g) once a day intravaginally for 10 days, followed by suppressive therapy of metronidazole gel twice a week for 4–6 months
Reporting and Partner Notification
  • Bacterial vaginosis is not a reportable disease.
  • Treatment of male sexual partners is not indicated and does not prevent recurrence.
  • No follow-up is necessary unless the patient is pregnant or symptoms recur.
Special Considerations
  • Routine screening for BV during pregnancy is not recommended, but can screen & Tx at 12–16 weeks in high-risk pregnancies. However, symptomatic women should be tested and treated.
  • Treatment of asymptomatic BV in women with a previous preterm birth may reduce the risk of preterm prelabour rupture of the membranes and low birth weight
  • Treat with oral antibiotics: oral metronidazole and clindamycin are not contraindicated during pregnancy or breastfeeding.
  • Topical antibiotics have no effect on preterm birth, though topical clindamycin treatment has been associated with adverse outcomes in the newborn when used in pregnancy
  • Testing should be repeated after 1 month to ensure that therapy was effective.
HIV – The same therapy is recommended for HIV-positive as for HIV-negative patients.

Treatment of uncomplicated vulvovaginal candidiasis

Asymptomatic – Treatment is unnecessary
  • Intravaginal, over-the-counter azole ovules and creams (e.g., clotrimazole, miconazole)
  • Fluconazole 150 mg PO in a single dose. (Contraindicated in pregnancy)
  • Topical and oral azoles are equally effective, Oil-based ovules and creams may cause latex condoms or diaphragms to fail.
  • In most cases, expect resolution of symptoms in 2–3 days
Complicated vulvovaginal candidiasis
  • Defined as recurrent VVC, severe VVC, a non-albicans species or occurring in a compromised host.
Recurrent VVC (RVVC)
  • ≥ 4 of VVC in a 12-month period.
  • Confirm the diagnosis of RVVC by obtaining a vaginal culture and full identification of the isolated species, which should be used to guide therapy. Non-albicans Candidaspecies are found in 10–20% of patients with RVVC. Conventional antifungal therapy is not as effective against some of these species
  • Tx requires induction, usually followed by a 6-month maintenance regimen
  • For patients prone to RVVC who require a course of antibiotics, prophylactic topical or oral azoles, such as fluconazole 150 mg PO, can be given at the start of the antibiotic course and once a week during the duration of the course 
Treatment of recurrent vulvovaginal candidiasis (RVVC)
Induction treatment
  • Fluconazole 150 mg PO once every 72 hours for three doses  – Contraindicated in pregnancy
  • Topical azole for 10–14 days
  • Boric acid 300–600 mg gelatin capsule intravaginally once a day for 14 days.  Less mucosal irritation experienced when 300 mg used. Contraindicated in pregnancy


  • Each individual episode of RVVC caused by C. albicans usually responds to a course of oral or topical azoles, with a longer course usually more effective than a shorter one.
  • Without maintenance therapy, VVC recurs in 50% of patients within 3 months. Start maintenance therapy as soon as initial treatment has been completed.
Maintenance treatment
  • Fluconazole 150 mg PO once a week
  • Ketoconazole 100 mg PO once a day 
    • Patients receiving long-term ketoconazole should be monitored for hepatotoxicity
  • Itraconazole 200–400 mg PO once a month
  • Clotrimazole 500 mg intravaginally once a month
  • Boric acid 300 mg capsule intravaginally for 5 days each month beginning the first day of the menstrual cycle


  • Duration of maintenance therapy is a minimum of 6 months. After 6 months, discontinue therapy and observe.
  • Relapse rate is high, with approximately 60% of women relapsing within 1–2 months of discontinuing maintenance therapy.
  • If recurrence occurs, treat the episode and then reintroduce a maintenance regimen.
  • Fluconazole and boric acid are contraindicated in pregnancy.
  • Oil-based ovules and creams may cause latex condoms or diaphragms to fail.
Severe VVC
  • Extensive vulvar erythema, edema, excoriation or fissure formation.
Treatment of severe vulvovaginal candidiasis
  • Fluconazole 150 mg PO once every 72 hours for two doses. Contraindicated in pregnancy
  • Topical azole for 10–14 days
Non-albicans VVC
  • Most commonly due to C. glabrata, which is 10- to 100-fold less susceptible to azoles than C. albicans.
Treatment of non-albicans vulvovaginal candidiasis
Initial treatment
  • Boric acid 600 mg capsule intravaginally once a day for 14 days 
  • Flucytosine cream 5 g intravaginally once a day for 14 days 
  • Amphotericin B 50 mg suppository intravaginally once a day for 14 days
    • Mild external irritation reported in 10%
  • Flucytosine 1 g PLUS amphotericin B 100 mg (combined in a lubricating jelly) administered intravaginally once a day for 14 days  Efficacy 100% (in 4 patients)
If symptoms recur
  • Retreat with boric acid 600 mg capsule intravaginally once a day for 14 days FOLLOWED BY: alternate-day boric acid for several weeks or 100,000 units of nystatin vaginal suppositories once a day for 3-6 months
    • No safety data available for long-term use of boric acid.Footnote51
Compromised host
  • Corticosteroids, uncontrolled diabetes.
  • C. glabrata and other non-albicans species are isolated more frequently in women with diabetes than in those without.
  • Treat with a longer (10–14 day) course of an intravaginal azole OR boric acid600 mg capsule intravaginally once a day for 14 days
Reporting and Partner Notification
  • Vulvovaginal candidiasis is not a reportable disease.
  • Routine screening and treatment of male partners is not indicated. However, male sexual partners should be treated if Candida balanitis is present. Use a topical azole cream twice a day for 7 days.
  • No follow-up necessary unless symptoms persist or recur.
  • Consider C&S of yeast if not responding to appropriate therapy or if infection recurs.
Special Considerations
  • Only topical azoles are recommended for treatment of vulvovaginal candidiasis during pregnancy. Treatment for 7 days may be necessary.
  • The treatment of candidiasis is the same in HIV-positive as it is in HIV-negative individuals.
  • Vaginal candidiasis is often recurrent and more severe in HIV-positive women and, in some cases, will require more aggressive and long-term therapy.

Treatment of trichomoniasis

  • Metronidazole 2 g PO in a single dose
  • Metronidazole 500 mg PO bid for 7 days
  • Efficacy 82–88% for both regimens; increases to 95% if partner also treated
  • Intravaginal metronidazole gel is not effective
Reporting and Partner Notification
  • Trichomoniasis is a reportable disease in some jurisdictions.
  • Current partners should be treated for trichomoniasis, regardless of symptoms (it is not necessary to screen partners for trichomonas). The majority of men infected with T. vaginalis are asymptomatic, but some may have mild urethritis. Treat sexual partners with the same therapy as recommended for the case.
  • No follow-up necessary unless symptoms recur; usually due to reinfection.
  • Prevalence of metronidazole-resistant T. vaginalis estimated at 5%. Usually responds to high-dose metronidazole.
Special Considerations
  • Trichomoniasis may be associated with premature rupture of the membranes, preterm birth and low birth weight.
  • Symptomatic pregnant women should be treated with metronidazole 2 g PO in a single dose for symptom relief. An alternative treatment is metronidazole 500 mg PO bid for 7 days.
    • It is not known whether treatment will improve pregnancy outcomes
  • It is not recommended that asymptomatic pregnant women be treated
  • Metronidazole is not contraindicated during pregnancy or breastfeeding.
HIV – The same therapy is recommended for HIV-positive as for HIV-negative patients.

The Use of Live Lactobacilli to Restore Normal Vaginal Flora

  • Lactobacilli preparations are commonly used in the treatment of BV and VVC. One small randomized trial in healthy women showed that the use of oral Lactobacilli was safe and resulted in increased vaginal Lactobacilli and decreased yeast as compared to the placebo group.
  • However, in a more recent, well-conducted randomized, controlled trial of 278 women, oral and vaginal L. rhamnosus was ineffective in the prevention of post-antibiotic VVC.
  • Two randomized, controlled trials have studied the use of a topical L. acidophilus–low dose estriol combination, one in the management of BV, the other for several infections (BV, VVC, trichomoniasis). Both showed a statistically significant greater reduction in symptoms and microscopic restoration of normal flora than the placebo group.


Posted in 83 STI, 99 Priority Topics, FM 99 priority topics

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