Bacterial vaginosis
From IDWiki
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)
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:
- Clindamycin 300 mg PO bid for 7 days
- Clindamycin ovule (vaingal suppository) 100 mg intravaginally daily for 3 days
- Tinidazole 2 g PO daily for 2 days
- Tinidazole 1 g PO daily for 5 days
Pregnant Women
- Metronidazole 500 mg PO bid for 7 days
- Metronidazole 250 mg PO tid for 7 days
- Clindamycin 300 mg PO bid for 7 days
