Efficacy of benzathine penicillin G in group A streptococcal pharyngitis: reevaluation

J Pediatr. 1987 May;110(5):783-7. doi: 10.1016/s0022-3476(87)80024-0.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Child
  • Follow-Up Studies
  • Humans
  • Penicillin G / therapeutic use*
  • Penicillin G Benzathine / therapeutic use*
  • Pharyngitis / drug therapy*
  • Pharyngitis / etiology
  • Pharynx / microbiology
  • Streptococcal Infections / drug therapy*
  • Streptococcus pyogenes / drug effects
  • Streptococcus pyogenes / isolation & purification
  • Time Factors


  • Penicillin G
  • Penicillin G Benzathine