A 17-year-old pregnant teen reports some vaginal itching and odor associated with a thin discharge. There is no associated pain. She is unmarried and has had three lifetime sexual partners. On examination, her discharge is visible (Figure 76-1). It is thin and off-white. Wet prep examination shows that more than 50 percent of the epithelial cells are clue cells (Figure 76-2). Tests for STDs are all negative. The patient is treated with oral metronidazole 500 mg bid for 7 days with good results.

Bacterial vaginosis (BV) is a clinical syndrome resulting from alteration of the vaginal ecosystem. It is called a vaginosis, not a vaginitis, because the tissues themselves are not actually infected, but only have superficial involvement. Women with BV are at increased risk for the acquisition of HIV, Neisseria gonorrhoeae, Chlamydia trachomatis, and herpes simplex virus (HSV)-2, and they have increased risk of complications after gynecologic surgery.¹

BV is associated with adverse pregnancy outcomes, including premature rupture of membranes, preterm labor, preterm birth, intraamniotic infection, and postpartum endometritis. However, the only established benefit of BV therapy in pregnant women is the reduction of symptoms and signs of vaginal infection.¹

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  Vaginal bacteriosis.

  
  
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  Corynebacterium vaginosis/vaginalis/vaginitis.

  
  
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  Gardnerella vaginalis/vaginosis.

  
  
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  Haemophilus vaginalis/vaginitis.

  
  
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  Nonspecific vaginitis.

  
  
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  Anaerobic vaginosis.

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  BV is estimated to be the most prevalent cause of vaginal discharge or malodor in women presenting for care in the US. However, more than 50 percent of women with BV are asymptomatic.¹ It accounts for more than 10 million outpatient visits per year.² The worldwide prevalence is unknown.

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  Hydrogen peroxide-producing Lactobacillus is the most common organism composing normal vaginal flora after puberty.¹ In BV, normal vaginal lactobacilli are replaced by high concentrations of anaerobic bacteria such as Mobiluncus, Prevotella, Gardnerella, Bacteroides, and Mycoplasma species.^1,2

  
  
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  The hydrogen peroxide produced by the Lactobacillus may help in inhibiting the growth of atypical flora.

  
  
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  The odor of BV is caused by the aromatic amines produced by the altered bacterial flora in the vagina. These aromatic amines include putrescine and cadaverine—aptly named to describe their foul odor.

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  Multiple male or female partners.^1,3

  
  
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  A new sex partner.¹

  
  
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  Douching.⁴

  
  
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  Lack of condom use.¹

  
  
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  Lack of vaginal lactobacilli.¹

  
  
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  Prior BV infection.¹

Clinical Features