The pH is the vagina is normally acidic (pH <4.5). Normal vaginal bacteria (predominantly Lactobacillus) thrive in this acidic environment; whereas, other more harmful bacteria prefer a more alkaline environment. Conditions that disrupt the normal acid pH of the vagina may predispose to infection with harmful bacteria or other microorganisms that overgrow in the less acidic environment shifting the bacterial population, or that gain entry through sexual activity (sexually transmitted diseases).
The causes of bacterial vaginosis are relatively poorly understood; however, the following activities have been associated with a greater risk of infection:
- having a new sex partner,
- having multiple sex partners
- douching
- using an intrauterine contraception device (IUD)
Bacterial vaginosis is suggested by the presence of “Clue cells” seen during microscopic examination of vaginal fluids. Symptoms associated with bacterial vaginosis commonly include a thin white or grey discharge and an unpleasant odor (fish-like odor, especially after intercourse). Additional symptoms may include pain, itching and burning. Vaginosis may also be asymptomatic, where the woman is not experiencing symptoms, but microscopic examination shows the absence of Lactobacillus (long, Gram-positive rods) and the presence of “clue cells”.
“Clue cells” are vaginal epithelial cells that are so coated with bacteria that their edges are difficult to discern. The bacterial population associated with vaginosis include Gram-negative and Gram-variable rods and cocci (e.g. G. vaginalis, Prevotella, Porphyromonas, and peptostreptococci), and curved Gram-negative rods (Mobiluncus). Inflammatory cells are not usually seen in microscopic preparations of vaginal fluids from women with bacterial vaginosis – one of the reasons why the condition is referred to as vaginosis rather than vaginitis. The term vaginitis suggests an infection associated with the presence of inflammatory cells (neutrophils), commonly seen in vulvovaginal candidiasis or Trichomonas vaginalis infections.
Bacterial vaginosis is diagnosed by clinical symptoms and laboratory microscopic examination of vaginal fluids (Gram stain). Three of the following clinical criteria are required to diagnose bacterial vaginosis:
- thin, white discharge that smoothly coats vaginal walls,
- presence of clue cells on microsopic examination,
- pH >4.5 of vaginal fluid,
- fish-like odor of vaginal discharge (the addition of 10% KOH results in a release of fishy odor, and is commonly referred to as the "whiff" test.
Bacterial vaginosis may resolve without treatment; however, the Centres for Disease Control and Prevention (CDC) recommend that all women with symptoms be treated to avoid complications that include a greater predisposition to sexually transmitted diseases and/or pelvic inflammatory disease. Evidence does not suggest that bacterial vaginosis is sexually transmitted; therefore male partners are not generally treated. Bacterial vaginosis may spread between female sexual partners, however.
Symptomatic pregnant women should be treated, as well as asymptomatic pregnant women with history of premature delivery or low birth weight babies. The CDC estimated that as many as 16% of pregnant women in the U.S. have bacterial vaginosis.
Bacterial vaginosis during pregnancy has been associated with:
- premature rupture of the membranes,
- preterm labor,
- preterm birth,
- intraamniotic infection, and
- postpartum endometritis.
The recommended treatments for bacterial vaginosis include the antibiotics metronidazole or clindamycin, both of which are safe for use during pregnancy. A 7-day treatment protocol is generally used: shorter treatment regimens may be associated with recurrence of bacterial vaginosis. It is extremely important to complete the full treatment protocol prescribed by your physician, even after symptoms resolve.
Related Content:
Vaginitis: Vulvovaginal Candidiasis
Source:
Bacterial vaginosis (CDC Fact Sheet)
