What is bv infection

Last updated: April 1, 2026

Quick Answer: A BV infection (bacterial vaginosis) is a vaginal condition caused by overgrowth of harmful bacteria, presenting with grayish vaginal discharge and fishy odor, and is curable with antibiotic treatment.

Key Facts

Understanding BV Infection

A bacterial vaginosis (BV) infection represents a disruption of the vaginal microecosystem. The healthy vagina maintains a delicate balance of microorganisms, dominated by Lactobacillus species that produce lactic acid. This acidic environment (pH 3.8-4.5) naturally suppresses the growth of harmful bacteria. BV infection occurs when this balance is disrupted, allowing pathogenic bacteria to proliferate.

Infection Mechanism

In a BV infection, the population of beneficial Lactobacillus bacteria dramatically decreases, and their place is taken by anaerobic bacteria including Gardnerella vaginalis, Prevotella species, and Mycoplasma. These bacteria produce compounds called biogenic amines that cause the characteristic fishy odor. The loss of lactic acid production causes vaginal pH to rise, further promoting pathogenic bacterial growth and creating a self-perpetuating cycle.

Infection Symptoms

Women with BV infection typically experience one or more of the following:

Approximately 50% of women with BV infection are asymptomatic and discover the condition only during routine medical examination.

Diagnosis

Healthcare providers diagnose BV infection using clinical criteria and laboratory testing. Amsel's criteria require three of four findings: abnormal discharge, elevated vaginal pH (>4.5), positive whiff test (fishy odor when discharge is mixed with potassium hydroxide), and presence of clue cells on microscopy. Nucleic acid amplification tests (NAATs) provide highly sensitive and specific diagnosis.

Treatment of BV Infection

BV infection responds well to antibiotic therapy with cure rates exceeding 90%. First-line treatments include:

Complications and Prevention

Untreated BV infection carries significant health risks. It increases susceptibility to sexually transmitted infections by 3-5 fold and can progress to pelvic inflammatory disease, endometritis, and tubo-ovarian abscess. In pregnant women, untreated BV infection substantially increases risk of preterm delivery and low birth weight. Prevention includes avoiding douching, limiting sexual partners, practicing safer sex, and maintaining vaginal health.

Related Questions

What is the treatment for BV infection?

BV infection is treated with antibiotics including metronidazole or clindamycin, administered orally or vaginally for 5-7 days. Treatment cures the infection in approximately 90% of cases.

What causes a BV infection?

BV infection is caused by bacterial imbalance when protective Lactobacillus species decline and harmful anaerobic bacteria overgrow. Risk factors include sexual activity, douching, and antibiotic use.

How long does a BV infection last without treatment?

Some BV infections resolve on their own within weeks, but others persist indefinitely if untreated. Medical treatment is recommended to prevent complications and hasten resolution.

Sources

  1. CDC - Bacterial Vaginosis public domain
  2. Wikipedia - Bacterial Vaginosis CC-BY-SA-4.0