What is the first line antibiotic for Group A streptococcal (strep A) infection?

From the Guidelines

Penicillin is the first-line antibiotic treatment for Group A streptococcal (Strep A) infections. For most uncomplicated infections, oral penicillin V (phenoxymethylpenicillin) is typically prescribed at a dose of 250-500 mg two to four times daily for 10 days, as recommended by the Infectious Diseases Society of America 1.

Key Considerations

• The dose and duration of penicillin treatment are crucial for preventing complications like rheumatic fever and post-streptococcal glomerulonephritis.
• In patients with penicillin allergy, alternatives include first-generation cephalosporins (if no history of anaphylaxis to penicillin), macrolides such as erythromycin (500 mg four times daily for 10 days), or clindamycin (300 mg three times daily for 10 days) 1.
• Complete adherence to the full 10-day course is essential even if symptoms resolve earlier.
• Penicillin remains the preferred treatment because Group A streptococcus has maintained susceptibility to it over decades, and it has a narrow spectrum of activity which minimizes disruption to normal gut flora and reduces the risk of antimicrobial resistance 1.

Special Situations

• For patients with recurrent pharyngitis and laboratory evidence of group A streptococcus, antibiotics may be considered in specific situations, such as during a community outbreak of acute rheumatic fever or invasive group A streptococcal infection 1.
• In these cases, the treatment regimen should be individualized based on the patient's medical history, allergy status, and the severity of the infection.

Conclusion Not Applicable - Direct Answer Only

The first-line antibiotic for Group A streptococcal (Strep A) infection is penicillin, with a recommended dose of 250-500 mg two to four times daily for 10 days 1.

From the Research

First Line Antibiotic for Group A Streptococcal Infection

• The first line antibiotic for Group A streptococcal (strep A) infection is penicillin V, with a recommended course of 10 days 2.
• Amoxicillin is also considered a first-line antibiotic, with a recommended course of 10 days 2.
• First-generation cephalosporins are recommended for patients with nonanaphylactic allergies to penicillin 2.

Alternative Antibiotics

• Macrolides, such as azithromycin, may be considered as an alternative antibiotic, but there is significant resistance to azithromycin and clarithromycin in some parts of the United States 2.
• Cephalosporins may be more effective than penicillin for early clinical cure and bacteriological eradication, but the benefits of using these antibiotics do not outweigh the harms of their unnecessary use 3.
• Carbacephem may provide better symptom resolution post-treatment in adults and children compared to penicillin, but the evidence is of low certainty 4.

Dosage and Administration

• Penicillin V is recommended to be taken 500 mg twice daily for 10 days 5.
• Azithromycin may be taken as a single dose, but the evidence for its effectiveness is of very low certainty 4.
• Amoxicillin is recommended to be taken for 10 days, but the optimal dosage is not specified in the available evidence.