Penicillin treatment failure in group a streptococcal tonsillopharyngitis:No genetic difference found between strains isolated from failures and nonfailures

Despite penicillin (pcV) treatment, tonsillopharyngitis caused by group A s treptococci (GAS) is associated with bacterial failure rates as high as 25% . The reason for this rate of failure is not fully understood. One explanat ion might be that certain DNA profiles of GAS strains are responsible for t reatment failures. Using arbitrarily primed polymerase chain reaction (AP-P CR), we compared the DNA profiles of GAS strains from 4 patients with sever al treatment failures following pcV treatment of tonsillopharyngitis with t he profiles of strains of the same T type from patients who were clinically and bacteriologically cured after a single course of pcV. The isolates wer e obtained during the same time period and from the same geographic area. T hirty-seven strains of T types 4, 12, and R28 were investigated. Eleven dif ferent DNA profiles could he detected with the AP-PCR technique. Five DNA p rofiles were identified as T type 12, 3 as T type 4, and 3 as T type R28. T he DNA profiles of the strains from the 4 patients with several treatment f ailures differed, but all isolates from each one of these patients exhibite d the same or a very similar profile. The DNA profiles of the failure strai ns were also represented in nonfailure strains. Treatment failure in these 4 patients therefore seems to be due to insufficient eradication of GAS, ra ther than to reinfection with a new strain. The finding that the same DNA p rofile can be present in both failure and nonfailure strains suggests that the treatment failure may be to some extent host-related and not only due t o bacterial factors.