Treatment of beta-hemolytic streptococcal pharyngitis with cefaclor or penicillin. Efficacy and interaction with beta-lactamase-producing organisms in the pharynx.

The recommended treatment for group A beta-hemolytic streptococcal pharyngitis has continued to be penicillin given in parenteral or oral form. Treatment failures, as determined by the continued presence of the streptococcal organism in the pharynx, however, do occur in 6% to 25% of patients treated with penicillin. Furthermore, beta-lactamase produced by other bacteria in the pharynx could potentially inactivate the penicillin, resulting in increased treatment failures or infection relapses. A study was undertaken to compare the efficacy of cefaclor, which is relatively resistant to inactivation by beta-lactamase, with penicillin for eradicating the group A beta-hemolytic streptococcal organism from the throats of 93 patients with pharyngitis. Additionally, extensive cultures for potential beta-lactamase-producing organisms were conducted on 37 patients; 27% of these had one or more pharyngeal organisms that were producing beta-lactamase. No statistically significant difference was found between the clinical responses or the bacteriological cure rates of those treated with cefaclor and those treated with penicillin when stratified by the presence or absence of beta-lactamase-producing organisms. The prevalence of beta-lactamase-producing organisms in the pharynx, however, was increased after treatment with penicillin, whereas no change was noted following treatment with cefaclor.