Recurrent Streptococcal Pharyngotonsillitis Studies on etiology and treatment

In acute pharyngotonsillitis group A streptococci (GAS) is the etiological agent in 30-50% of cases. Phenoxymethylpenicillin (pcV) is the drug of choice in Sweden. However, the failure rate is as high as 5-25% and further pcV treatment is followed by still higher failure rates. The background of failures remains largely elusive. The aim of the studies was: 1 To investigate the short- and long-term efficacy of pcV versus clindamycin in patients with GAS pharyngotonsillitis who failed on pcV treatment. 2 To examine failure and non-failure strains considering so called penicillin-tolerance. 3 To compare the DNA-profiles of failure and non-failure strains. 4 To evaluate the kinetics of pcV, loracarbef and clindamycin in tonsillar surface fluid (TSF). Bacterial failure was defined as presence of GAS of the primary T-type within two weeks after completing therapy. 239 patients with GAS pharyngotonsillitis were treated with pcV for ten days. 53 patients with bacterial failure were randomized to treatment with either pcV or clindamycin and were then followed for one year. Failure and non-failure strains were screened for penicillin tolerance and some were subjected to time killing tests. Using AP-PCR the DNA-profiles of failure and non-failure strains were compared. PcV, loracarbef and clindamycin were investigated regarding concentration in TSF during and after ten days treatment of GAS pharyngotonsillitis. CRP and orosomucoid were analyzed throughout the investigation period. In the pcV group 14/22 patients yielded GAS in the throat culture after the first retreatment, compared to 0/26 in the clindamycin group. In the first three months 15/22 patients in the pcV group yielded one or more positive cultures for GAS, all of the same T-type as compared to 3/26 in the clindamycin group, which all were of another T-type. The difference between the groups was later reduced. However, clindamycin could prevent further treatment failures for at least the first three months after failure in pcV treated GAS pharyngotonsillitis. No penicillin tolerant strains could be identified and penicillin tolerance seems to be of no significance in failures of pcV treated GAS pharyngotonsillitis. The strains were of three different T-types, and eleven different clones were identified. The same clones were found in both failures and non-failures. PcV was found in TSF during the first three day period of treatment, after which the concentration declined. Loracarbef and clindamycin showed more longstanding concentration in TSF, with measurable values even after therapy. This may contribute to their capacity to eradicate GAS in patients who failed on pcV treatment of GAS pharyngotonsillitis. CRP was of no significance as indicator of GAS as a cause of pharyngotonsillitis.