Recurrent Bacterial Vaginosis

Recurrent bacterial vaginosis is three or more episodes of bacterial vaginosis in 12 months. It results from persistent loss of lactobacilli and regrowth of anaerobes, with biofilm on the vaginal wall.

• Relapse within 6 months of treatment is common.
• Risk factors are douching, new or multiple sexual partners, intrauterine device use, smoking and female sexual partners.
• Treatment needs an induction course followed by suppressive therapy.

Thin grey-white homogeneous discharge with a fishy odour, worse after intercourse or menses, with little vulval inflammation.

• Few symptoms in some women; itching and soreness are not typical.
• Differential diagnosis: trichomoniasis, vulvovaginal candidiasis, aerobic vaginitis, cervicitis, desquamative inflammatory vaginitis, retained foreign body.
• Complications: pelvic inflammatory disease, increased risk of acquiring HIV and other sexually transmitted infections, preterm birth and post-procedure infection.

Use any three of the Amsel criteria, or a Nugent score of 7 to 10.

• Thin homogeneous discharge; vaginal pH above 4.5; positive amine (whiff) test; clue cells on wet mount.
• Gram stain with Nugent score where available.
• NAAT or culture to exclude trichomoniasis, gonorrhoea and chlamydia.
• HIV and syphilis tests; review contraceptive method and douching history.

Treat the episode with an induction course, then give suppressive therapy for 4 to 6 months.

• Supportive: stop douching and scented products; use condoms; avoid irritants; stop smoking; consider changing from a copper intrauterine device to another method if recurrence follows insertion; treat female sexual partners.
• Pharmacological: induction: metronidazole 400 mg oral 12-hourly for 7 days, or clindamycin 2 percent cream 5 g intravaginal nightly for 7 days. Suppression: metronidazole 0.75 percent gel 5 g intravaginal twice weekly for 4 to 6 months, or metronidazole 400 mg oral twice weekly for 3 to 6 months, or boric acid 600 mg intravaginal capsule nightly for 21 days after induction followed by metronidazole gel twice weekly for 4 to 6 months. Avoid alcohol during metronidazole and for 48 hours afterwards.
• Procedures: none.
• Special groups: in pregnancy give metronidazole 400 mg oral 12-hourly for 7 days at any trimester, or clindamycin 300 mg oral 12-hourly for 7 days; avoid boric acid. In breastfeeding mothers use metronidazole 400 mg oral 12-hourly for 7 days rather than a single 2 g dose, and continue breastfeeding. In severe liver impairment limit metronidazole to 400 mg oral once daily.
• Red flags: lower abdominal pain, fever, cervical motion tenderness, preterm labour in pregnancy, treatment failure after suppression.
• Follow-up: review at 4 weeks and at 3 and 6 months; repeat microscopy when symptoms return.