Characterization of consecutive Streptococcus pyogenes isolates from patients with pharyngitis and bacteriological treatment failure: Special reference to prtF1 and sic/drs

To analyze bacteriological treatment failure in streptococcal pharyngitis, 40 consecutive Streptococcus pyogenes isolates from 18 patients were charac terized. For 17 patients, isolates were indistinguishable with respect to e mm type, random amplified polymorphic DNA pattern, and presence of prtF1 en coding the fibronectin-binding protein F1. prtF1 was detected only in the 1 1 isolates (4 patients) with emm12 and in the single isolate with emm6. Fur ther analysis by vir(mga) regulon typing, sequencing of sic encoding the st reptococcal inhibitor of complement from 19 isolates with emm1 (9 patients) , and sequencing of drs (distantly related sic) from 11 isolates with emm12 revealed distinct sic alleles with insertions and/or deletions in sic that corresponded to differences in restriction patterns of the vir( mga) regul on only for paired isolates of 2 patients. Among isolates with emm12, 2 nov el drs alleles were found. Analysis of these data suggests that neither the presence of prtF1 nor the diversification of sic / drs is required for the persistence of S. pyogenes in pharyngitis.