Amoxicillin is Highly Effective Against Group A Streptococcal Infections
Yes, Group A Streptococcus (GAS) responds excellently to amoxicillin, which is explicitly listed as an effective treatment option alongside penicillin and is often preferred in young children due to better palatability. 1
Microbiological Efficacy
- No clinical isolate of Group A Streptococcus anywhere in the world has been documented to be resistant to penicillin or its congeners, including amoxicillin. 1
- Amoxicillin is specifically FDA-approved for treatment of infections due to susceptible (β-lactamase-negative) isolates of Streptococcus species, including α- and β-hemolytic strains. 2
- The Infectious Diseases Society of America explicitly states that amoxicillin is among the antibiotics proven effective in treating Group A streptococcal pharyngitis. 1
Clinical Evidence Supporting Amoxicillin
- Amoxicillin at 40 mg/kg/day demonstrated superior bacteriologic cure rates (79.3%) compared to standard-dose penicillin V (54.5%) in pediatric GAS pharyngitis, with significantly better clinical cure rates (87.9% vs 70.9%). 3
- Once-daily amoxicillin dosing has been shown to be as effective as multiple-daily dosing regimens in eradicating GAS, with no statistical difference in bacterial load reduction or negative culture rates. 4
- Six-day amoxicillin therapy (50 mg/kg/day divided twice daily) showed comparable efficacy to 10-day penicillin V therapy, with GAS eradication rates of 83.7% vs 85.3%, respectively. 5
Guideline-Based Treatment Recommendations
- Penicillin remains the agent of choice, but amoxicillin is often used in place of oral penicillin V to treat young children, with equal efficacy. 1
- The choice of amoxicillin over penicillin V is primarily related to acceptance of the taste of the suspension in pediatric patients. 1
- The American Heart Association has recommended once-daily amoxicillin dosing as an acceptable regimen for treating GAS pharyngitis. 6
Dosing Considerations
- Standard dosing is 40-50 mg/kg/day for children, with evidence supporting both once-daily and divided dosing regimens for 10 days. 3, 4
- Once-daily amoxicillin therapy (up to 1000 mg maximum) has been validated as effective, potentially improving compliance while maintaining efficacy. 7, 6
- Treatment should be continued for a minimum of 48 to 72 hours beyond the time that the patient becomes asymptomatic or evidence of bacterial eradication has been obtained. 2
Important Clinical Caveats
- Amoxicillin should only be used for β-lactamase-negative GAS isolates, though this is universally the case for Group A Streptococcus. 2
- The medication should be taken at the start of a meal to minimize gastrointestinal intolerance. 2
- Amoxicillin is an appropriate alternative for patients who cannot tolerate penicillin V but do not have true penicillin allergy. 8, 7