BV Flashcards
What is it??
Bacterial vaginosis (BV) is a clinical condition characterized by a shift in vaginal microbiota away from Lactobacillus (hydrogen peroxide producing) species toward more diverse bacterial species, including facultative anaerobes (esp gram negative rods)
What are the 3 characteristics of BV
BV is characterized by three alterations in the vaginal environment [1]:
●A shift in vaginal microbiota from Lactobacillus species to one of high bacterial diversity, including facultative anaerobes.
●Production of volatile amines by the new bacterial microbiota.
●Resultant rise in vaginal pH to >4.5 (normal vaginal pH of estrogenized women ranges from 4.0 to 4.5).
What is the most common cause vaginal discharge in woman of childbearing age
BV
50% of cases
prevalence 30%
What are the major bacteria in woman with BV
The major bacteria detected in women with BV are Gardnerella vaginalis, Prevotella species, Porphyromonas species, Bacteroides species, Peptostreptococcus species, Mycoplasma hominis, and Ureaplasma urealyticum, as well as Mobiluncus, Megasphaera, Sneathia, and Clostridiales species [8,16]. Fusobacterium species and Atopobium vaginae are also common.
Pathophysiology of BV
Production of amines – Hydrogen peroxide-producing lactobacilli appear to be important in preventing overgrowth of the anaerobes normally present in the vaginal microbiota. With the loss of lactobacilli, pH rises and massive overgrowth of vaginal anaerobes occurs. These anaerobes produce large amounts of proteolytic carboxylase enzymes, which break down vaginal peptides into a variety of amines that are volatile, malodorous, and associated with increased vaginal transudation and squamous epithelial cell exfoliation, resulting in the typical clinical features observed in patients with BV (see ‘Clinical features’ below). The rise in pH also facilitates adherence of G. vaginalis to the exfoliating epithelial cells.
What are risk factors for BV?
Sexual activity is a risk factor for BV and most experts believe that BV does not occur in women who have never had sexual contact of any type
BV is highly prevalent (25 to 50 percent) in women who have sex with women (WSW),
Sexually transmitted infections – The presence of other sexually transmitted infections appears to be associated with an increased prevalence of BV
Race and ethnicity – While higher rates of BV have been reported in minority populations, it is not clear if this finding reflects genetic, socioeconomic, behavioral, or other differences
Other – In addition to sexual and infectious risk factors, most studies indicate that douching and cigarette smoking are risk factors for acquisition of BV among sexually active women
Symptoms
Fifty to 75 percent of women with BV are asymptomatic
Symptomatic women typically present with vaginal discharge and/or vaginal odor
The discharge is off-white, thin, and homogeneous; the odor is an unpleasant “fishy smell” that may be more noticeable after sexual intercourse and during menses
What does BV increase the risk of?
Pregnant women with BV are at higher risk of preterm delivery [74-77]. (See “Bacterial vaginosis: Treatment”, section on ‘Pregnant’.)
●BV is a risk factor for [78-80]:
- Endometrial bacterial colonization
- Plasma-cell endometritis
- Postpartum fever
- Posthysterectomy vaginal cuff cellulitis
- Postabortal infection
BV is a risk factor for HIV acquisition and transmission [55,81,82].
●BV is a risk factor for acquisition of herpes simplex virus type 2, gonorrhea, chlamydia, and trichomonas infection
What is the amsel criteria
The diagnosis of BV is usually based on Amsel criteria, which are simple and useful in an office practice where microscopy is available [67,70]. The first three findings are sometimes also present in patients with trichomoniasis (table 1).
Amsel criteria for diagnosis of BV (at least three criteria must be present) [93]:
●Homogeneous, thin, grayish-white discharge that smoothly coats the vaginal walls.
●Vaginal pH >4.5.
●Positive whiff-amine test, defined as the presence of a fishy odor when a drop of 10 percent potassium hydroxide (KOH) is added to a sample of vaginal discharge.
●Clue cells on saline wet mount (picture 1A-B). Clue cells are vaginal epithelial cells studded with adherent coccobacilli that are best appreciated at the edge of the cell (picture 2). For a positive result, at least 20 percent of the epithelial cells on wet mount should be clue cells. The presence of clue cells diagnosed by an experienced microscopist is the single most reliable predictor of BV
What are clue cells ?
Clue cells are vaginal epithelial cells studded with adherent coccobacilli that are best appreciated at the edge of the cell (picture 2). For a positive result, at least 20 percent of the epithelial cells on wet mount should be clue cells. The presence of clue cells diagnosed by an experienced microscopist is the single most reliable predictor of BV
Treatment
Not pregnant + symptomatic
- metronidazole 500 mg bd for 7/7
(2g stat no longer recommended low efficacy)
or clindamycin
What are SE of metronidazole
Side effects of metronidazole (oral or vaginal) include a metallic taste, nausea (in 10 percent of patients), transient neutropenia (7.5 percent), a disulfiram-like effect with alcohol, prolongation of International Normalized Ratio in patients taking vitamin K antagonists (eg, warfarin), and peripheral neuropathy
ok in first trimester (although does cross the placenta)
Do we screen and treat BV to reduce preterm birth>
2013 cochrane review
nearly 8000 pregnant woman
Abs eradicated the infection
did not reduce the odds of preterm birth or PPROM
But there is an association RR 2 for PTB linked with chorioamnionitits
2015 cochrane review in woman at risk of PTB (prev PTB) and BV, antibiotics reduced their risk of PTB
ACOG - do not screen and treat for BV
Screening before gynae procedures
Reasonable to treat before hysterectomy or TOP to prevent procedural complications
Reductions in post op infections 10-75%
Insufficient evidence to make a conclusion about BV before IUCD insertion
Should partners be screened
Not male partners
If female partner - 25-5% concordant infection
No change in behavior is linked to reduction of persistence
