Dear laslab: As an introduction to your question here is some background information. A normal discharge is made up from exfoliated vaginal skin cells, bacteria, and secretions from the cervix and vaginal walls. While
as many as 30 types of bacteria can be found in normal vaginal discharge, about 95% of a healthy vaginal bacteria population consists of lactobacilli. There are several subtypes of lactobacilli, but the most important type produces hydrogen peroxide. Just like hydrogen peroxide is used to clean cuts and scrapes on the surface of external skin, the hydrogen peroxide produced by the lactobacilli helps decrease the numbers of undesirable bacteria such as E. Coli, a common bowel bacteria responsible for urinary tract infections. A healthy vaginal pH is relatively acidic (pH 3.8-4.5). An acidic pH also discourages undesirable bacteria.
Group B strep, E. Coli, and Staph aureus (normal skin bacteria) were frequently cultured in a group of 631 women, many of whom had no symptoms (Donder, 2002). In a study of 141 GYN surgical patients, Group B strep was found in the vaginal secretions of 20% (Song, 1999). This suggests that many types of bacteria can be a part of the vaginal ecology.
laslab, E.Coli may, or may not, be the culprit. All we know was that it was identified on the vaginal culture so it was treated in hopes that symptoms would disappear. It may be some other condition which was the cause, but the antibiotics were helpful. For a decade there was a condition called "desquamative vaginitis" (symptoms of redness, irritation, thin discharge) which seemed to be successfully treated with clindamycin. Symptoms which returned were retreated with the clindamycin. More recently, vaginitis experts are asserting that this was not an infection--rather a variant of the autoimmune disorder lichen planus which can be found in the vagina and mouth.
Amazingly, one can also have your exact symptoms when there is an overgrowth of the beneficial, hydrogen peroxide producing lactobacilli. In this situation the overgrowth produces a very burning, stinging discharge. Cultures show "normal flora".
I would urge you to continue to follow up with your GYN. If need be you can be referred to a specialist in a vulvar pain clinic. These GYN's tend to see all the uncommon vulvar and vaginal pain conditions (including lichen planus). Some women are fortunate enough to have the vaginal ecology return to a better balance over time--even minimal treatment.
Yours,
Jane