Bacterial vaginosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alara Ece Dagsali, M.D.[2]
Synonyms and keywords: Anaerobic vaginosis; Nonspecific vaginitis
Overview
Bacterial vaginosis (BV) is a clinical condition characterized by a shift in vaginal microbiota away from Lactobacillus species toward more diverse bacterial species, including facultative anaerobes. The altered microbiome causes a rise in vaginal pH and symptoms that range from none to very bothersome (eg, abnormal vaginal discharge and odor). Future health implications of BV include, but are not limited to, increased susceptibility to other sexually transmitted infections (STIs), including HIV, and preterm birth.
BV is characterized by three alterations in the vaginal environment:
- 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 and reduced lactic acid production.
- Resultant rise in vaginal pH to >4.5 (normal vaginal pH of estrogenized females typically ranges from 4.0 to 4.5).
Historical Perspective
BV is the most common cause of abnormal vaginal discharge in females of childbearing age, accounting for 40 to 50 percent of vaginitis cases. In the United States, the National Health and Nutrition Examination Survey (NHANES), which included results from self-collected vaginal swabs from over 3700 women, estimated the prevalence of BV was 29 percent in the general population of women aged 14 to 49 years and 50 percent in African American women. This included both symptomatic and asymptomatic infection. Worldwide, a meta-analysis of studies from seven regions of the world found that the prevalence of Nugent-diagnosed BV was 23 to 29 percent among women of reproductive age, with small variations according to the population studied.
Pathophysiology
Processes that contribute to clinical BV include a shift in vaginal microbiota from hydrogen peroxide-producing lactobacilli to anaerobic bacteria, release of amines, and production of a protective biofilm.
- ""Altered vaginal microbiota and dysbiosis"" – BV represents a complex change in the vaginal microbiota characterized by a reduction in concentration of the normally dominant lactobacilli, which produce hydrogen peroxide and lactic acid, and an increase in concentration of other organisms, especially anaerobic Gram-negative rods [9-13]. Age also appears to impact the vaginal microbial community [14]. The absence of clinical signs of inflammation is the basis for the term "vaginosis" rather than "vaginitis." Some authors use the term "dysbiosis" to reflect the microbial imbalance in the vaginal microbiota that can ultimately impact vaginal function and lead to negative health consequences
Processes that contribute to clinical BV include a shift in vaginal microbiota from hydrogen peroxide-producing lactobacilli to anaerobic bacteria, release of amines, and production of a protective biofilm.
- ""Commonly associated bacteria"" – The major bacteria detected in females 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. Fusobacterium species and Atopobium vaginae (now renamed Fannyhessea vaginae) [19] are also common.
- ""Bacteria identified with ribosomal DNA probes"" – The difference in vaginal microbiota between those with and without BV was illustrated in a study that used broad range ribosomal DNA probes to determine the vaginal microbiota of 27 women with BV and 46 controls [1]. Overall, 35 bacterial phylotypes were identified in women with BV, including 16 that were newly recognized. Women with BV had a mean of 12.6 phylotypes (range 9 to 17) per sample compared with 3.3 phylotypes (range 1 to 6) per sample in women without BV. The organisms newly identified by polymerase chain reaction included fastidious bacteria termed "BV-associated bacteria (BVAB) 1, 2, and 3" in the Clostridiales order, which appear to be specific indicators of BV [20]. Subsequent studies suggest BVAB1, now known as Candidatus lachnonocura vaginae, has likely been mistaken for Mobiluncus on microscopy and Nugent scoring [21-23]. Additional studies have also further characterized BVAB3, which is now known as Mageebacillus indolicus, and identified other bacterial species in the human vagina, including the novel strains Peptoniphilaceae DNF01163 and Prevotellaceae DNF00733, and [24-27].
Causes
Differentiating Bacterial vaginosis from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Amsel Criteria | History and Symptoms | Physical Examination | Laboratory Findings | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies