In a pure state, bacterial vaginosis is a non-inflammatory process and is not an infection. The organisms that constitute bacterial vaginosis are all derived from the endogenous microflora, and these bacteria are present in a concentration that exceeds 106 bacteria/ml of vaginal fluid. In the presence of bacterial vaginosis, the concentration of Lactobacillus is less than 103 bacteria/ml of vaginal fluid. These bacterial concentrations are significant considering the potential for infection when bacterial vaginosis exits. In the obstetric patient bacterial vaginosis has been associated with preterm labor, premature rupture of amniotic membranes, premature delivery, septic abortion, chorioamnionitis, and postpartum endometritis; in the gynecologic patient it is associated with endometritis, post-hysterectomy pelvic infection, and salpingitis. Even though there are no hard data that demonstrate a cause and effect relationship between these conditions and bacterial vaginosis, there are data that show a strong correlation between bacterial vaginosis and some of the aforementioned infections. Although there is controversy concerning the role of bacterial vaginosis in diseases of the genital tract, there is no doubt that the bacterial constituents that make up bacterial vaginosis are almost all significant pathogens capable of causing serious infections.

The treatment of bacterial vaginosis is based on the presence of an overgrowth of obligate anaerobic bacteria. However, the fact that there is a significant decrease in the hydrogen ion concentration or increase in pH should be taken into consideration. The advocated treatment regimens all have about the same efficacy, approximately 65 — 75%. This low success rate is likely because of the failure to re-establish the appropriate pH in the vaginal ecosystem, thus preventing Lactobacillus from regaining dominance.

The antimicrobial agents of choice are clindamycin and metronidazole. If the patient’s microflora has not progressed to one that is dominated by obligate anaerobic bacteria, but is in an intermediate stage or dominated by Gardnerella vaginalis, these antibiotic treatments will likely fail since these agents are not active against this bacterium. Therefore, when examining the vaginal discharge, if clue cells and aggregates of bacteria are seen one should suspect the vaginal microflora is in transition and most likely dominated by Gardnerella vaginalis. This diagnosis can be reenforced by a positive whiff test or the presence of a fish-like odor. Successful treatment for this stage of bacterial vaginosis development can be accomplished by administering a first-generation cephalosporin.

Treatments for established bacterial vaginosis are:

Oral antibiotic agents

(1) Metronidazole 250 mg three times a day for 7 days;

(2) Metronidazole 500 mg twice a day for 7 days;

(3) Metronidazole 2 g as a single dose; or

(4) Clindamycin 300 mg twice a day for 7 days.

Intravaginal preparations

(1) Clindamycin cream 2% one applicator-full at bedtime for 7 nights; or

(2) Metronidazole gel 0.75% one applicator-full twice a day for 7 days

Available variations of the intravaginal medications are metronidazole gel dosed for 5 days and clindamycin ovules for 3 days. There is no significant advantage in terms of efficacy with the shorter dosage regimens compared with standard regimens. It has been the author’s experience that these shorter dosing regimens tend not to be as effective (this is anecdotal information).

When treating bacterial vaginosis, it is important to consider the pH of the vaginal environment. A patient treated for bacterial vaginosis should be examined 1 week after completion of therapy. If the vaginal pH has not returned to the normal range of 3.8 — 4.2, there is a good chance that her bacterial vaginosis will return or a bacterium other than Lactobacillus will become dominant. When examining the vaginal discharge microscopically, the physician should focus on the noticeable absence of bacteria. Following treatment, it is not uncommon to find that the vaginal discharge appears relatively healthy. The squamous epithelial cells are well estrogenized, there are no clue cells, and WBC are scarce, but there is a noticeable absence of bacteria. If the vagina is checked and the pH is 5 or higher, this should indicate that the vaginal ecosystem has not been restored to a healthy state.

This patient should then be treated with a vaginal acidifying agent, such as boric acid vaginal capsules 600 mg twice a day for 14 days, Aci jel one applicatorfull twice a day for 14 — 21 days, or Relagard® vaginal gel one applicator-full twice a day for 14 — 21 days. Although there are no published reports addressing this issue, I have found that when the vaginal pH is restored to 4.S or lower there is a better chance for achieving restoration of a healthy vaginal ecosystem characterized by a microflora dominated by Lactobacillus.

Treatment of chronic, persistent, or recurrent bacterical vaginosis

It is difficult to define recurrent bacterial vaginosis, but for practical purposes as far as the patient is concerned, if she has a second episode of bacterial vaginosis then it is recurrent. However, it is probably appropriate to say that if a patient has four or more episodes of bacterial vaginosis within a 12-month period, it could be considered recurrent. If the patient experiences only brief periods of time without bacterial vaginosis, for example 1 — 3 weeks, then it would be fair to label her condition as chronic. If the patient has no or only extremely brief periods without bacterial vaginosis symptoms, then the condition could be labeled as persistent bacterial vaginosis.

Treatment of these conditions requires a comprehensive approach. A detailed history should be repeated with a focus on the use of genital hygiene products, sexual practices, and medications, especially antibiotic use and herbal remedies. Patients will often take a daily antibiotic for acne and fail to mention this because they are only taking one antibiotic a day. However, a single dose of antibiotic can affect the composition of the vaginal microflora.

Patients should refrain from sexual activity because there appears to be a relationship between the frequency of sexual intercourse and the recurrence of bacterial vaginosis. Although there appears to be a similar relationship between the risk factors associated with acquisition of sexually transmitted diseases (STDs) and the acquisition of bacterial vaginosis, the latter is not considered an STD. However, many women report that they have recurrent episodes of bacterial vaginosis only after having sexual intercourse with their partner. These are usually women in long-term monogamous relationships. In those cases, treatment of the male sexual partner with oral metronidazole appears to have some benefit.

Patients with chronic and/or persistent bacterial vaginosis should be treated with a combination of an oral agent, either metronidazole or clindamycin, and an intravaginal acidifying agent. If re-examination reveals a noticeable decrease in the bacteria but the pH has not decreased to within the normal range, then the intravaginal administration of the acidifying agent should continue. The use of the antimicrobial agent should be limited because continued administration will result in further alterations of the vaginal microflora. I will close this discussion with the fact that at present bacterial vaginosis is not considered an infection but rather an alteration of the endogenous microflora. Therefore, it does not seem plausible that bacterial vaginosis can be successfully corrected with an antimicrobial agent. Successful treatment of bacterial vaginosis depends upon restoring the vaginal ecosystem to a healthy state.

 

Selections from the book: “Vaginitis: Differential Diagnosis and Management” (2003).

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