Lactobacillus
Lactobacillus, particularly hydrogen peroxide-producing species, appears to help prevent other vaginal microorganisms from multiplying to a level where they cause symptoms. (Note: Lactobacillus acidophilus is not one of the species of Lactobacillus identified as playing a protective role in vaginal flora.) The microorganisms involved in BV are very diverse, but include Gardnerella vaginalis, Mobiluncus, Bacteroides, and Mycoplasma. A change in normal bacterial flora including the reduction of lactobacillus, which may be due to the use of antibiotics or pH imbalance, allows more resistant bacteria to gain a foothold and multiply. In turn these produce toxins which effect the body's natural defenses and make re-colonization of healthy bacteria more difficult.Most cases of bacterial vaginosis occur in sexually active women between the ages of 15 and 44, especially after contact with a new partner. Condoms may provide some protection and there is no evidence that spermicide increases BV risk. Although BV appears to be associated with sexual activity, there is no clear evidence of sexual transmission.
