Kim K S, Kaplan E L
J Pediatr. 1985 Nov;107(5):681-4. doi: 10.1016/s0022-3476(85)80392-9.
Despite uniform susceptibility of group A streptococci to penicillin, failure to eradicate group A streptococci is not uncommon in patients receiving penicillin for treatment of pharyngitis. We explored the possibility that penicillin tolerance could explain this phenomenon. We examined 48 group A streptococcal isolates from 48 patients successfully treated with penicillin (streptococci eradicated) and 92 isolates from 37 patients (one to four isolates per patient) who failed to respond to penicillin therapy (streptococci not eradicated). Penicillin tolerance was recognized by the gradient-replicate plate method and by time-kill experiments with penicillin concentrations of 16 times the minimal inhibiting concentrations. Tolerance was identified in 25% (23 of 92) of the isolates from the treatment failure group, in contrast to none of the strains from the treatment success group. Characterization of the strains by M and T typing revealed no predominant type(s) among the tolerant strains. These findings suggest that penicillin tolerance may be responsible for some instances of failure of penicillin to eradicate group A streptococci from the upper respiratory tract of individuals with streptococcal tonsillitis or pharyngitis.
尽管A组链球菌对青霉素普遍敏感，但在接受青霉素治疗咽炎的患者中，未能根除A组链球菌的情况并不罕见。我们探讨了青霉素耐受性能否解释这一现象的可能性。我们检查了来自48例成功接受青霉素治疗的患者（链球菌已根除）的48株A组链球菌分离株，以及来自37例对青霉素治疗无反应的患者（链球菌未根除）的92株分离株（每位患者1至4株分离株）。通过梯度复制平板法和使用16倍最小抑菌浓度的青霉素进行时间杀灭实验来识别青霉素耐受性。在治疗失败组的分离株中，25%（92株中的23株）表现出耐受性，而治疗成功组的菌株无一表现出耐受性。通过M和T分型对菌株进行鉴定，结果显示耐受性菌株中没有占主导地位的类型。这些发现表明，青霉素耐受性可能是导致青霉素无法从患有链球菌性扁桃体炎或咽炎的个体上呼吸道根除A组链球菌的部分原因。
