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Evaluation of Amoxicillin and Amoxicillin-Clavulanate (Augmentin) for Antimicrobial Postexposure Prophylaxis
Raymond M Slay1, Graham J Hatch2, Judith A Hewitt1
1National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Abstract:
Amoxicillin is a broad-spectrum antibiotic used to treat a variety of gram-positive and gram-negative infections, such as infections of the ear, nose, and throat, genitourinary tract, skin, and lower respiratory tract; gonorrhea; and Helicobacter pylori. The prophylactic benefit of both amoxicillin and Augmentin (amoxicillin-clavulanate for use against β-lactamase-expressing bacteria) was evaluated for inhalation anthrax in cynomolgus macaques in 2 studies. A pilot study on amoxicillin-clavulanate that used a portion of the study animals demonstrated empirically that dosing twice a day was efficacious. In a subsequent study on both amoxicillin and amoxicillin-clavulanate that used the remaining study animals, the animals were treated orally every 12 hours on days 1-28 postchallenge and followed for an additional 60 days (total of 88 days from day of aerosol challenge to when the animals were culled). The animals from each treatment arm of the 2 studies were completely protected. All untreated animals succumbed to the infection. The degree of protection observed in this study suggests that both amoxicillin and amoxicillin-clavulanate, administered prophylactically over a period of 28 days after a lethal exposure to Bacillus anthracis spores, is sufficient for full protection.
Insights
Amoxicillin and amoxicillin-clavulanate offer complete protection against anthrax when given prophylactically for 28 days after exposure. Untreated macaques did not survive, highlighting the efficacy of these antibiotics for anthrax prevention.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Amoxicillin is a broad-spectrum antibiotic effective against various bacterial infections.
- Inhalation anthrax, caused by Bacillus anthracis, is a severe and often fatal disease.
- The prophylactic efficacy of amoxicillin and amoxicillin-clavulanate against anthrax was previously unevaluated.
Purpose of the Study:
- To evaluate the prophylactic benefit of amoxicillin and amoxicillin-clavulanate against inhalation anthrax.
- To determine the optimal dosing regimen for amoxicillin-clavulanate prophylaxis.
Main Methods:
- Two studies were conducted in cynomolgus macaques exposed to Bacillus anthracis spores.
- Animals received oral amoxicillin or amoxicillin-clavulanate every 12 hours for 28 days post-exposure.
- A pilot study informed the dosing regimen, with a subsequent study confirming efficacy.
Main Results:
- All animals treated with amoxicillin or amoxicillin-clavulanate demonstrated complete protection from lethal anthrax.
- Untreated control animals succumbed to the infection.
- A 28-day prophylactic course was sufficient for full protection.
Conclusions:
- Amoxicillin and amoxicillin-clavulanate are highly effective prophylactic agents against inhalation anthrax.
- A 28-day oral administration regimen provides complete protection following Bacillus anthracis exposure.
- These findings support the use of amoxicillin-based antibiotics for anthrax post-exposure prophylaxis.
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