What antibiotics are used to treat streptococcal infections?

From the Guidelines

Penicillin is the first-line antibiotic for treating streptococcal infections, particularly Group A Streptococcus (GAS). For adults with strep throat, oral penicillin V (250-500 mg twice daily for 10 days) or amoxicillin (500 mg twice daily for 10 days) is typically recommended, as supported by the Infectious Diseases Society of America guidelines 1.

Key Considerations

• The choice of antibiotic should be based on the patient's allergy history and the severity of the infection.
• For patients with a penicillin allergy, alternatives such as first-generation cephalosporins (e.g., cephalexin), macrolides (e.g., azithromycin or clarithromycin), and clindamycin can be used 1.
• Completing the full course of antibiotics is crucial to prevent complications like rheumatic fever and ensure complete eradication of the bacteria.

Treatment Options

• For individuals without penicillin allergy:
  • Penicillin V (oral): 250 mg twice daily or 3 times daily for children, and 250 mg 4 times daily or 500 mg twice daily for adolescents and adults 1.
  • Amoxicillin (oral): 50 mg/kg once daily (max = 1000 mg) or 25 mg/kg twice daily (max = 500 mg) for 10 days 1.
• For individuals with penicillin allergy:
  • Cephalexin (oral): 20 mg/kg/dose twice daily (max = 500 mg/dose) for 10 days 1.
  • Azithromycin (oral): 12 mg/kg once daily (max = 500 mg) for 5 days 1.
  • Clarithromycin (oral): 7.5 mg/kg/dose twice daily (max = 250 mg/dose) for 10 days 1.

Important Notes

• Streptococci remain largely susceptible to penicillin, which works by inhibiting bacterial cell wall synthesis, making it highly effective against these gram-positive organisms.
• The guidelines from the Infectious Diseases Society of America provide evidence-based recommendations for the diagnosis and management of group A streptococcal pharyngitis 1.
• Other studies have also evaluated the effectiveness of different antibiotics for treating streptococcal infections, including a study from 1997 that recommended penicillin as the first-line treatment 1 and a study from 1992 that discussed the importance of completing the full course of antibiotics to prevent complications 1.

From the FDA Drug Label

Erythromycin tablets are indicated in the treatment of infections caused by susceptible strains of the designated microorganisms in the diseases listed below: Upper respiratory tract infections of mild to moderate degree caused by Streptococcus pyogenes; Azithromycin Tablets, USP are indicated for the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms in the specific conditions listed below ... Pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy. Uncomplicated skin and skin structure infections due to Staphylococcus aureus, Streptococcus pyogenes, or Streptococcus agalactiae

The antibiotics used to treat streptococcal infections are:

• Erythromycin 2
• Azithromycin 3 and 3 These antibiotics are effective against susceptible strains of Streptococcus pyogenes and other streptococcal species.

From the Research

Antibiotics Used to Treat Streptococcal Infections

• Penicillin and amoxicillin are first-line antibiotics for the treatment of streptococcal infections, with a recommended course of 10 days 4
• First-generation cephalosporins are recommended for patients with nonanaphylactic allergies to penicillin 4
• Cephalosporins, macrolides, and carbacephem have been compared to penicillin in the treatment of group A beta-hemolytic streptococcal (GABHS) tonsillopharyngitis, but the evidence is uncertain regarding their comparative efficacy 5
• Azithromycin has been compared to amoxicillin in the treatment of GABHS tonsillopharyngitis in children, but the evidence is uncertain regarding their comparative efficacy 5

Resistance Patterns

• Resistance rates to erythromycin and ceftriaxone have increased over time, while levofloxacin resistance and multidrug-resistant (MDR) rates are higher in adult groups 6
• The MDR rate of Streptococcus pneumoniae has significantly increased during the recent 10 years, and is higher in patients with a history of hospitalization within 90 days and sinusitis 6
• Penicillin resistance in strains of S. pneumoniae approaches 40% in some areas of the United States, and the incidence of high-level resistance has increased by 60-fold during the past 10 years 7

Treatment Recommendations

• Beta-lactam antibiotics, such as penicillin G, amoxicillin, amoxicillin/clavulanate, cefuroxime, cefotaxime, or ceftriaxone, are recommended for the treatment of nonmeningeal pneumococcal infections 7
• Cefotaxime or ceftriaxone, with the addition of vancomycin until susceptibility is known, are recommended for the treatment of meningitis 7