The vaginal microbiome contains a community of bacteria, including Gardnerella vaginalis. An overgrowth of this bacterium can disrupt the natural balance, leading to bacterial vaginosis (BV). This imbalance is characterized by a decrease in beneficial Lactobacillus bacteria and a rise in anaerobic bacteria like Gardnerella. For individuals with symptoms, antibiotic therapy is the standard treatment to manage BV by targeting the bacterial overgrowth.
Common Antibiotic Prescriptions
The primary antibiotics prescribed for bacterial vaginosis are Metronidazole and Clindamycin, which are considered first-line treatments. These drugs are effective because they target anaerobic bacteria, the category that includes Gardnerella vaginalis. By interfering with the growth of these bacteria, the antibiotics help to reduce their population and allow the natural balance of the vaginal flora to be reestablished.
Metronidazole can be administered as an oral tablet or a topical vaginal gel. The oral regimen involves taking a 500 mg tablet twice daily for seven days. Alternatively, a 0.75% metronidazole vaginal gel is applied directly into the vagina once daily for five days. The topical application delivers medication to the site of the infection and results in lower systemic absorption compared to the oral route.
Clindamycin is also available in both oral and topical formulations. The oral form is a 300 mg capsule taken twice daily for seven days. Topical treatments include a 2% vaginal cream or vaginal ovules. The cream is applied once daily for seven days, while the 100 mg ovules are inserted nightly for a shorter, three-day course. Studies have shown that a three-day course of Clindamycin ovules can be as effective as a seven-day course of oral Metronidazole. Topical application is an option for minimizing systemic side effects like gastrointestinal issues.
Alternative Antibiotic Therapies
When first-line treatments like Metronidazole or Clindamycin are not appropriate, providers may use alternative antibiotics. This can occur if a patient has an allergy to the primary drugs or if an infection did not resolve with standard therapy. Two common alternatives are Tinidazole and Secnidazole, which function by disrupting the DNA of anaerobic bacteria to stop their growth.
Tinidazole is an oral tablet taken in different dosing schedules. A provider might recommend a 2-gram dose taken once daily for two days or a 1-gram dose taken once daily for five days. It is effective against many of the same bacteria that cause BV and is often reserved for cases where initial treatment has failed.
Secnidazole has a longer half-life in the body, which allows it to be administered as a single-dose therapy. The treatment consists of a 2-gram packet of oral granules that are sprinkled onto soft food, like applesauce or yogurt, and consumed once. The convenience of a one-time dose makes it a viable alternative for some individuals.
Important Considerations During Treatment
When taking Metronidazole or Tinidazole, it is important to avoid alcohol. Consuming alcohol with these medications can trigger a disulfiram-like reaction. This occurs because the antibiotic interferes with the normal breakdown of alcohol, leading to an accumulation of a toxic byproduct called acetaldehyde.
The symptoms of this reaction can be severe and include:
- Intense nausea
- Vomiting
- Skin flushing
- Dizziness
- A throbbing headache
To prevent this, individuals should avoid all forms of alcohol during treatment and for at least 48 to 72 hours after completing the course. This includes beverages and other products containing alcohol.
Antibiotic treatment can also disrupt the beneficial bacteria in the vaginal microbiome, which can lead to a secondary yeast infection (candidiasis). Symptoms of a yeast infection include itching, burning, and a thick, white discharge. If this occurs, a healthcare provider may suggest an over-the-counter antifungal cream or prescribe an oral antifungal pill. Other common side effects of these antibiotics can include a metallic taste in the mouth with Metronidazole or general gastrointestinal upset.
Managing Recurrent Infections
Bacterial vaginosis can become a recurring issue, which is defined as experiencing three or more episodes within a single year. The high rate of recurrence, over 50% within a year of treatment, happens because initial antibiotics may not fully eradicate bacteria that can form a protective layer known as a biofilm.
When infections become recurrent, a different treatment strategy is often required. The approach involves a longer course of suppressive antibiotic therapy following an initial course to clear the active infection. A common suppressive regimen is using 0.75% Metronidazole vaginal gel twice a week for four to six months. This long-term application reduces the frequency of recurrence, though the benefit may not persist after therapy stops.
In addition to suppressive antibiotic therapy, other strategies may be recommended to support long-term vaginal health and prevent future episodes. Boric acid suppositories are one such option; a regimen might involve using a 600 mg suppository daily for 21 days following antibiotic treatment. Boric acid is thought to help by disrupting the biofilms that protect BV-associated bacteria. The use of specific probiotic strains, particularly those containing Lactobacillus crispatus, is another supportive measure aimed at restoring a healthy vaginal microbiome.