From the Guidelines
Penicillin G is the first-line antibiotic for treating alpha-hemolytic streptococcal infections, with a recommended dosage of 12-18 million U/day i.v. either in 4-6 doses or continuously for 4 weeks 1.
Treatment Options
- For patients with penicillin allergy, alternatives include vancomycin 30 mg/kg/day i.v. in 2 doses for 4 weeks 1.
- For more severe infections requiring intravenous therapy, ceftriaxone 2 g/day i.v. or i.m. in 1 dose can be used for 4 weeks 1.
- Combination therapy with gentamicin 3 mg/kg/day i.v. or i.m. in 1 dose for 2 weeks may be considered for certain severe infections 1.
Important Considerations
- Alpha-hemolytic streptococci, which include Streptococcus viridans group and Streptococcus pneumoniae, remain largely susceptible to beta-lactam antibiotics 1.
- Treatment duration varies based on infection site and severity, with longer courses (4-6 weeks) needed for endocarditis 1.
- Antibiotic susceptibility testing is recommended for serious infections as resistance patterns can vary 1.
Special Cases
- For patients with impaired renal function, penicillin G is preferred due to its lower risk of nephrotoxicity 1.
- For patients with prosthetic valve endocarditis, 6-week therapy with penicillin G, ceftriaxone, or vancomycin is recommended 1.
From the FDA Drug Label
Because some strains are resistant to azithromycin, susceptibility tests should be performed when patients are treated with azithromycin. Pharyngitis/tonsillitis caused by Streptococcus pyogenes as an alternative to first-line therapy in individuals who cannot use first-line therapy. NOTE: Penicillin by the intramuscular route is the usual drug of choice in the treatment of Streptococcus pyogenes infection and the prophylaxis of rheumatic fever.
The best antibiotic to treat alpha hemolytic strep is not directly stated in the label, penicillin is mentioned as the usual drug of choice for Streptococcus pyogenes infection. Azithromycin may be used as an alternative in individuals who cannot use first-line therapy. 2
From the Research
Antibiotic Treatment for Alpha Hemolytic Strep
- The best antibiotic to treat alpha hemolytic strep is not explicitly stated in the provided studies, as they primarily focus on group A beta-hemolytic streptococcal pharyngitis or other types of streptococcal infections 3, 4, 5, 6, 7.
- However, a study from 1997 found that all 278 alpha- and nonhemolytic streptococcal isolates were susceptible to teicoplanin and vancomycin 4.
- Another study from 1999 noted that the carriage rate of non-pneumococcal alpha-hemolytic streptococci increased after antibiotic therapy, and many of these isolates were multidrug-resistant 5.
- A 2021 review of different antibiotic treatments for group A streptococcal pharyngitis found that cephalosporins, macrolides, and carbacephem may be effective alternatives to penicillin, but the evidence was largely uncertain or of low certainty 6.
- A study from 2003 compared the efficacy of penicillin and amoxicillin in children with group A beta-hemolytic streptococcal tonsillopharyngitis and found that amoxicillin may be superior to penicillin for bacteriologic and clinical cure 7.
Susceptibility of Alpha-Hemolytic Strep to Antibiotics
- A study from 1997 reported the following susceptibility rates for alpha- and nonhemolytic streptococci:
- Penicillin G: 79.1%
- Oxacillin: 87.8%
- Ampicillin: 66.9%
- Piperacillin: 98.2%
- Cefoxitin: 76.6%
- Cefuroxime: 96.8%
- Cefotaxime: 98.6%
- Ceftriaxone: 98.6%
- Cefepime: 98.6%
- Imipenem: 98.2%
- Ciprofloxacin: 59.7%
- Ofloxacin: 89.2%
- Doxycycline: 65.8%
- Tetracycline: 56.8%
- Clindamycin: 87.8%
- Erythromycin: 59%
- Clarithromycin: 74.9%
- Chloramphenicol: 98.9%
- Cotrimoxazole: 97.9%
- Rifampin: 97.5%
- Fosfomycin: 2.2% 4
Resistance Patterns
- The studies suggest that alpha-hemolytic streptococci can develop resistance to various antibiotics, including penicillin, macrolides, and fluoroquinolones 4, 5, 6.
- The use of antibiotics can disrupt the balance between different microbial populations, leading to the emergence of resistant strains 5.