Background
Microbiology
- Shift in vaginal flora from Lactobacillus to high bacterial diversity that includes facultative anaerobes
- The new flora includes: Gardnerella vaginalis, Prevotella species, Porphyromonas species, Bacteroides species, Peptostreptococcus species, Mycoplasma hominis, Ureaplasma urealyticum, Mobiluncus species, Megasphaera species, Clotridiales species, Fusobacterium species, and Atopobium species
Pathophysiology
- The new bacterial flora produce volatile amines, which increases the vaginal pH >4.5 (from the normal range of 4 to 4.5)
Clinical Manifestations
Diagnosis
Amsel Criteria
- Requires microscopy but not Gram staining
- At least three of the following criteria:
- Characteristic vaginal discharge: homogeneous, thin, grayish-white discharge that smoothly coats the vaginal walls
- Elevated pH >4.5
- Clue cells on saline wet mount, which are vaginal epithelial cells studded with adherent coccobacilli
- Positive whiff-amine test, where a fishy odor is detected after a drop of 10% KOH is added to a sample of vaginal discharge
Nugent Criteria
- Based on the Gram stain
- Considered the gold standard, but is more resource-intensive than wet mount microscopy used for Amsel criteria
| Score
|
Lactobacillus
|
Gardnerella and Bacteroides
|
Curved gram-variable bacilli
|
| 0
|
4+
|
0
|
0
|
| 1
|
3+
|
1+
|
1+ or 2+
|
| 2
|
2+
|
2+
|
3+ or 4+
|
| 3
|
1+
|
3+
|
|
| 4
|
0
|
4+
|
|
- Interpretation is based on total score:
- 0 to 3: normal
- 4 to 6: indeterminate
- 7 to 10: bacterial vaginosis
Others
- Culture is not relevant to diagnosis of bacterial vaginosis
Management
Non-Pregnant Woman
- First-line:
- Metronidazole 500 mg PO bid for 7 days
- Metronidazole gel 0.75% 5 g (one full applicator) intravaginally once daily for 5 days
- Clindamycin 2% cream 5 g (one full applicator) intravaginally at bedtime for 7 days
- Alternatives:
Pregnant Women
