Bacterial vaginosis (BV) and chlamydia are two common bacterial infections that affect the reproductive system. BV is caused by an overgrowth of bacteria naturally present in the vagina, while chlamydia is caused by the bacteria Chlamydia trachomatis. Antibiotics are the standard treatment for both BV and chlamydia.
The first-line antibiotics used to treat uncomplicated BV are:
- Metronidazole (Flagyl)
- Clindamycin (Cleocin)
- Tinidazole (Tindamax)
The antibiotics used to treat uncomplicated chlamydia are:
- Azithromycin (Zithromax)
Metronidazole and clindamycin can be used to treat both BV and chlamydia co-infections when taken together. Alternative antibiotics may be needed for complicated infections or cases of treatment failure.
Overview of BV and Chlamydia
BV and chlamydia are among the most prevalent sexually transmitted infections. In the United States, BV affects around 21.2 million women between the ages of 14-49 years old. Chlamydia is even more widespread, with over 1.7 million cases reported in 2017 alone. BV and chlamydia often occur together, with 10-30% of women diagnosed with BV also testing positive for chlamydia.
BV is caused by an imbalance in the bacteria naturally present in the vagina. Normally, beneficial lactobacilli dominate. In BV, harmful anaerobic bacteria like Gardnerella vaginalis proliferate and cause symptoms like:
- Thin, grey, foul-smelling vaginal discharge
- Fishy odor, especially after sex or during menstruation
- Itching or burning around the vagina
- Slight redness and swelling of the vulva
BV is associated with a variety of complications, including:
- Increased risk of sexually transmitted infections like chlamydia and gonorrhea
- Increased risk of acquiring HIV
- Pregnancy complications like premature delivery and low birth weight
- Post-surgical infections after procedures like hysterectomy and abortion
Chlamydia is caused by infection with Chlamydia trachomatis bacteria. It is spread through unprotected vaginal, anal, or oral sex. Many people with chlamydia are asymptomatic. When present, symptoms may include:
- Burning urination
- Unusual vaginal discharge
- Abdominal pain
- Painful sexual intercourse
- Bleeding between periods
If left untreated, chlamydia can spread to the uterus and fallopian tubes, causing pelvic inflammatory disease (PID). PID can lead to long-term complications like:
- Chronic pelvic pain
- Ectopic pregnancy
Antibiotic Treatment for BV
Antibiotics taken orally or applied intravaginally are the standard treatment for BV. The Centers for Disease Control and Prevention (CDC) recommends:
Metronidazole (Flagyl) is one of the most common antibiotics used to treat BV. It can be taken:
- Orally at 500 mg twice daily for 7 days
- As a single 2g oral dose
- Intravaginally as 0.75% gel, one applicator (5g) once daily for 5 days
Clinical cure rates with 7 days of oral metronidazole range from 70-80%. The single 2g dose has slightly lower efficacy but improves adherence. Intravaginal metronidazole gel may alleviate symptoms faster.
Clindamycin (Cleocin) is another first-line BV therapy, administered either:
- Orally at 300 mg twice daily for 7 days
- Intravaginally as 2% cream, one applicator (5g) at bedtime for 7 days
Oral and vaginal clindamycin have similar BV cure rates as 7-day metronidazole regimens.
Tinidazole (Tindamax) is a newer antibiotic that can be used as:
- A single 2g oral dose
- 1g once daily for 5 days
In clinical studies, the 2g single tinidazole dose cured BV in 70-85% of women. The 5-day course has slightly higher efficacy.
Other BV Antibiotics
Other antibiotics that may sometimes be used for BV include:
- Secnidazole (Solosec) – 2g oral granules in a single dose
- Clindamycin (Cleocin) – vaginal ovules, 100 mg intravaginally once daily for 3 days
- Metronidazole extended release – 1.3g oral tablet once daily for 5 days
These regimens have similar efficacy to standard therapies but may be preferred in certain situations.
Antibiotic Treatment for Chlamydia
Chlamydia is treated with antibiotics that stop the bacteria from multiplying. CDC recommended treatments include:
Azithromycin (Zithromax) is the most commonly prescribed antibiotic for chlamydia. Treatment is a single 1g oral dose. Azithromycin is convenient as a single dose but can cause nausea and diarrhea.
Doxycycline is usually taken as 100 mg orally twice per day for 7 days. Doxycycline has good efficacy against chlamydia but cannot be taken by pregnant women.
The typical erythromycin regimen is 500 mg orally four times per day for 7 days. Gastrointestinal side effects are common with erythromycin.
Levofloxacin and Ofloxacin
These quinolone antibiotics may be used as alternatives for chlamydia treatment if first-line options are contraindicated. However, resistance is increasing.
- Levofloxacin – 500 mg orally once daily for 7 days
- Ofloxacin – 300 mg orally twice per day for 7 days
Treating BV-Chlamydia Co-Infections
Women diagnosed with both BV and chlamydia often receive combination antibiotic therapy. Common approaches include:
- Metronidazole (500 mg twice daily for 7 days) PLUS azithromycin (1g single dose)
- Clindamycin (300 mg twice daily for 7 days) PLUS azithromycin (1g single dose)
- Intravaginal clindamycin (for 7 days) PLUS azithromycin (1g single dose)
This treats both infections simultaneously. Doxycycline, erythromycin or levofloxacin can substitute azithromycin if needed.
Test of Cure
Women should be re-tested for chlamydia and BV 3-4 weeks after finishing treatment. This confirms the infections have resolved. If positive, retreatment with different antibiotics may be warranted.
Certain situations require alternative antibiotic regimens for optimal BV and chlamydia treatment:
Pregnant women with BV and chlamydia can be treated with:
- Metronidazole 500 mg orally twice daily for 7 days
- Amoxicillin 500 mg orally three times daily for 7 days
Intravaginal clindamycin is also considered safe in pregnancy. For chlamydia, azithromycin and amoxicillin are preferred over doxycycline.
For penicillin-allergic patients, doxycycline, azithromycin, and erythromycin are good BV-chlamydia options.
If BV or chlamydia persists after initial treatment, consider:
- Tinidazole 2g single oral dose (for BV)
- Levofloxacin 500 mg once daily for 7 days (for chlamydia)
Make sure partners are also treated to prevent reinfection.
HIV or Immunocompromised
Longer antibiotic courses may be used in these patients:
- Metronidazole 500 mg twice daily for 10-14 days (for BV)
- Doxycycline 100 mg twice daily for 10-14 days (for chlamydia)
To reduce the risk of contracting BV, chlamydia, and other STIs:
- Use condoms correctly every time you have sex
- Limit your number of sexual partners
- Get tested regularly if sexually active
- Have partners get tested/treated
- Avoid douching, which disturbs vaginal bacteria
Prompt antibiotic treatment can prevent long-term complications from these common infections.
BV and chlamydia frequently co-occur and require targeted antibiotic therapy. BV is treated with oral or vaginal metronidazole, clindamycin, or tinidazole. Recommended antibiotics for chlamydia include azithromycin, doxycycline, or erythromycin. Combining BV and chlamydia medications provides effective co-treatment. Alternative regimens may be needed in certain clinical situations. With appropriate antibiotics and preventive strategies, the impact of these infections can be greatly reduced.