From the Guidelines
Yes, metronidazole can be used to treat infections, specifically trichomoniasis and bacterial vaginosis (BV), with cure rates of approximately 90%-95% 1.
Key Points
- Metronidazole is the only oral medication available in the United States for the treatment of trichomoniasis 1.
- The recommended metronidazole regimens have resulted in high cure rates, and ensuring treatment of sex partners might increase the cure rate 1.
- For treatment of trichomoniasis, oral preparations of metronidazole are more efficacious than metronidazole gel, which is approved for treatment of BV 1.
- If treatment failure occurs, the patient should be re-treated with metronidazole 500 mg twice a day for 7 days 1.
- In cases of repeated treatment failure, a single 2-g dose of metronidazole once a day for 3-5 days can be used 1.
Treatment Considerations
- Follow-up is unnecessary for men and women who become asymptomatic after treatment or who are initially asymptomatic 1.
- Infections with strains of T. vaginalis that have diminished susceptibility to metronidazole can occur, but most of these organisms respond to higher doses of metronidazole 1.
From the FDA Drug Label
To reduce the development of drug-resistant bacteria and maintain the effectiveness of metronidazole tablets and other antibacterial drugs, metronidazole tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. Patients should be counseled that antibacterial drugs including metronidazole tablets should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold).
- Yes, metronidazole can be used to treat infections, but only those that are proven or strongly suspected to be caused by bacteria 2.
- It is essential to use metronidazole only for bacterial infections, as using it for other types of infections may not provide benefit to the patient and increases the risk of development of drug-resistant bacteria 2.
From the Research
Metronidazole's Therapeutic Uses
- Metronidazole is used to treat various infections, including:
- Trichomoniasis 3, 4, 5, 6, 7
- Amebiasis 3, 4, 6, 7
- Giardiasis 3, 4, 5, 6, 7
- Anaerobic bacterial infections 3, 4, 6, 7
- Bacteroides, Fusobacteria, and Clostridia infections 4, 7
- Rosacea, oral and dental infections, bone and joint infections, gynecologic infections, endocarditis, septicemia, and respiratory tract infections 4
- Metronidazole is also used as prophylaxis before surgical procedures 4
Metronidazole's Mechanism of Action and Efficacy
- Metronidazole has selective activity against anaerobic microorganisms, including bacteria and protozoa 3
- It is usually bactericidal at low concentrations, and its spectrum of activity encompasses almost all anaerobic bacteria and some capnophilic organisms 3
- Metronidazole is the most active antimicrobial agent against Bacteroides fragilis, the most resistant of anaerobic bacteria 3
- Kill-curve studies demonstrate that there is a 2 to 5 log decrease in the number of colony forming units of B. fragilis and Clostridium perfringens within one hour 3
Metronidazole's Side Effects and Resistance
- Metronidazole is well tolerated with mild to moderate side effects such as nausea, abdominal pain, and diarrhea 4, 5, 6
- Serious neurotoxicity, optic neuropathy, peripheral neuropathy, and encephalopathy have been reported in rare cases 4
- Resistance to metronidazole has been described in some strains of Trichomonas vaginalis and Bacteroides fragilis 3, 4