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Efficacy of benzathine penicillin G in group A streptococcal pharyngitis: reevaluation
Insights
Benzathine penicillin G achieved high eradication rates for group A streptococcal pharyngitis in children. However, 12% of patients experienced treatment failure, with higher rates in those with significant immune responses.
Area of Science:
- Pediatrics
- Infectious Diseases
- Microbiology
Background:
- Acute group A streptococcal pharyngitis is a common childhood infection.
- Benzathine penicillin G is a standard intramuscular treatment.
- Treatment failures necessitate understanding eradication rates and failure mechanisms.
Purpose of the Study:
- To determine the streptococcal eradication rate following benzathine penicillin G treatment in children with acute group A streptococcal pharyngitis.
- To explore potential reasons for treatment failure.
Main Methods:
- Study involved 66 children diagnosed with acute group A streptococcal pharyngitis.
- Intramuscular benzathine penicillin G was administered.
- Bacteriologic follow-up at 3 and 6 weeks assessed eradication.
- Minimum inhibitory and bactericidal concentrations determined penicillin susceptibility and tolerance.
Main Results:
- A bacteriologic treatment failure rate of 12% (8/66 patients) was observed.
- Failure rates were higher in patients with immunologically significant infections (21%) compared to those without antibody rises (8%).
- All isolated group A beta-hemolytic streptococcal strains remained susceptible to penicillin G, with no evidence of tolerance.
Conclusions:
- Benzathine penicillin G demonstrated a high group A streptococcal eradication rate, exceeding 90% in this pediatric cohort.
- Treatment failures were not attributed to penicillin-tolerant strains or a high proportion of asymptomatic carriers.
- Further investigation into factors influencing treatment outcomes in specific patient subgroups may be warranted.
Abstract:
The rate of streptococcal eradication after intramuscular administration of benzathine penicillin G in 66 children with acute group A streptococcal pharyngitis was determined and possible reasons for treatment failure explored. Bacteriologic treatment failure, defined as isolation of the same serotype at 3- or 6-weeks follow-up, occurred in eight (12%) patients. The treatment failure rate was 21% in those with immunologically significant infection, versus 8% in those without antibody rises (P greater than 0.1). All group A beta-hemolytic streptococcal (GABS) strains isolated from patients with treatment failure, both before and after benzathine penicillin G therapy, were exquisitely susceptible to penicillin G (minimum inhibitory concentration less than or equal to 0.02 microgram/mL), and none showed evidence of tolerance (minimum bactericidal concentration less than or equal to 0.04 microgram/mL). Thus, we found GABS eradication rates to exceed 10% in children given benzathine penicillin G. The failure rate did not appear to be related to enrichment of the patient population with a high proportion of asymptomatic carriers nor to the presence of penicillin-tolerant GABS.