Streptococcus Resistance Rates
Group A beta-hemolytic streptococcus (GABHS) remains universally susceptible to penicillin and amoxicillin with zero documented resistance worldwide, while macrolide resistance in the United States ranges from <5% to approximately 8%, with significant geographic variation. 1, 2
Penicillin and Amoxicillin Resistance
No penicillin resistance has ever been documented in Group A Streptococcus anywhere in the world, making penicillin V and amoxicillin the gold standard treatments with 100% susceptibility. 2, 3
All tested GABHS isolates in recent surveillance studies showed complete susceptibility to penicillin, ampicillin, cefotaxime, and ceftriaxone. 3
This remarkable lack of resistance persists despite over 40 years of widespread penicillin use for GABHS infections. 4
Macrolide Resistance Patterns
United States Rates
Macrolide resistance in the United States is <5% among Group A streptococci according to the most recent IDSA guidelines, though some data suggest rates may reach 5-8%. 1, 5, 2
Clindamycin resistance among invasive GABHS strains in the United States remains remarkably low at approximately 1%, with one Chicago study finding zero resistance among invasive strains. 1, 2
Historical data from 2005-2006 showed erythromycin resistance rates of 3.5-4.5% in community surveillance studies, representing an increase from 0% in 2002. 6
International Comparison
Germany reports macrolide resistance of 8.2% and Spain reports 18.3%, demonstrating significant geographic variation in resistance patterns. 1
Greece reported erythromycin resistance of 20.4% and clindamycin resistance of 18.8% in a 6-year surveillance study from a tertiary care hospital. 3
Austria documented 21.4% macrolide resistance among GABHS isolates, with 94.3% showing the M phenotype (efflux-mediated resistance). 7
Finland has experienced macrolide resistance as a major ongoing problem, though specific rates are not detailed in the provided evidence. 4
Viridans Group Streptococci Resistance
While not GABHS, viridans group streptococci show substantially higher resistance rates that merit awareness:
Penicillin resistance ranges from 13-50% and amoxicillin resistance is approximately 15% among viridans streptococci. 1
Macrolide resistance in viridans streptococci ranges from 22-58%, with erythromycin resistance averaging 38-41%. 1
Clindamycin resistance in viridans streptococci ranges from 4-27%, substantially higher than GABHS. 1
Other Antibiotic Resistance in GABHS
Tetracycline resistance affects approximately 40.8% of GABHS isolates, making tetracyclines inappropriate for treating GABHS infections. 3, 4
Sulfonamides show high resistance rates and fail to eradicate GABHS from the pharynx even when isolates appear susceptible in vitro, making them completely inappropriate for treatment. 5, 2, 4
Chloramphenicol resistance is uncommon at 6.9%, and fluoroquinolone resistance remains rare at 2% for levofloxacin. 3
All GABHS isolates remain susceptible to vancomycin, linezolid, teicoplanin, and tigecycline. 3
Clinical Implications
The critical distinction is that GABHS (the cause of strep throat and invasive infections) has zero penicillin resistance, while viridans streptococci (oral flora causing endocarditis) show substantial resistance. This explains why penicillin remains first-line for pharyngitis while endocarditis prophylaxis faces challenges. 1, 2
The rising macrolide resistance, even at relatively low U.S. rates, creates concern because macrolides serve as the primary alternative for penicillin-allergic patients. 5, 2 Geographic variation in resistance patterns emphasizes the importance of local surveillance data, though periodic rather than continuous monitoring is reasonable given the low overall resistance rates in the United States. 4