What is metronidazole?

From the Guidelines

Metronidazole is an antibiotic medication used to treat various bacterial and parasitic infections, and its use should be guided by the most recent and highest quality evidence available, such as the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.

Key Points

• Metronidazole works by stopping the growth of certain bacteria and parasites by interfering with their DNA.
• It is commonly prescribed for infections such as bacterial vaginosis, trichomoniasis, giardiasis, amoebiasis, and anaerobic bacterial infections including those causing abscesses or infections in the abdomen, skin, or other tissues.
• The typical adult dose ranges from 250-500 mg taken orally three times daily for 7-14 days, depending on the infection being treated, as recommended by studies such as the sexually transmitted diseases treatment guidelines 2002 1.
• Metronidazole is also available as a topical gel for rosacea, as a vaginal gel for bacterial vaginosis, and in intravenous form for serious infections.
• Common side effects include nausea, metallic taste, and potential disulfiram-like reactions with alcohol (causing flushing, headache, nausea, vomiting), so alcohol should be avoided during treatment and for at least 48 hours afterward.

Important Considerations

• The use of metronidazole should be guided by the most recent and highest quality evidence available, such as the 2017 Infectious Diseases Society of America clinical practice guidelines for the diagnosis and management of infectious diarrhea 1.
• The choice of antibiotic therapy, including metronidazole, should be based on the specific infection being treated and the susceptibility of the causative organism, as well as consideration of antimicrobial stewardship principles to reduce the emergence and spread of resistance 1.
• Metronidazole may be used as part of combination therapy for Helicobacter pylori, which causes stomach ulcers, and its effectiveness in this context has been evaluated in studies such as the management of Helicobacter pylori infection--the Maastricht IV/Florence Consensus Report 1.

From the FDA Drug Label

Metronidazole is classified therapeutically as an antiprotozoal and anti-bacterial agent. Metronidazole is an antiprotozoal and anti-bacterial agent.

• It is used to treat various infections
• Chemically, metronidazole is named 2-methyl-5-nitro-1H-imidazole-1- ethanol 2

From the Research

What is Metronidazole

• Metronidazole is a 5-nitroimidazole antibiotic that has selective activity against anaerobic microorganisms, including bacteria and protozoa 3.
• It is used to treat various infections, including trichomoniasis, amoebiasis, giardiasis, and anaerobic bacterial infections caused by Bacteroides species, fusobacteria, and clostridia 4, 5, 6.
• Metronidazole has been shown to be efficacious in the therapy of a variety of anaerobic infections, including non-traumatic brain abscesses, intraabdominal sepsis, pelvic suppuration, and necrotizing soft tissue infections 3.

Mechanism of Action and Spectrum of Activity

• Metronidazole is usually bactericidal at low concentrations and has a spectrum of activity that encompasses almost all anaerobic bacteria and some capnophilic organisms 3.
• It is active against protozoans like Entamoeba histolytica, Giardia lamblia, and Trichomonas vaginalis, as well as anaerobic bacteria such as Bacteroides and Fusobacterium spp. 5.
• Metronidazole is also effective against Gardnerella vaginalis, a pleomorphic Gram-variable bacterial bacillus 5.

Therapeutic Uses and Side Effects

• Metronidazole is used to treat a range of medical conditions, including trichomoniasis, amoebiasis, giardiasis, and anaerobic bacterial infections 4, 5, 6, 7.
• It is also used to treat rosacea, oral and dental infections, bone and joint infections, gynecologic infections, endocarditis, septicemia, and respiratory tract infections 7.
• Common side effects of metronidazole include nausea, abdominal pain, and diarrhea, while rare but serious side effects include neurotoxicity, optic neuropathy, peripheral neuropathy, and encephalopathy 7.