Typing of Streptococcus pyogenes strains isolated from throat infections in the region of Aachen, Germany

Background: Changes in the epidemiology of Streptococcus pyogenes infection s may be associated with the introduction and reappearance of individual se rotypes within a population. Materials and Methods: Typing of 216 consecutive isolates of S. pyogenes fr om patients with pharyngitis in the region of Aachen, Germany, was performe d by sequencing the emm gene, slide-agglutination of the T-antigen and dete rmining the serum opacity reaction (SOR). Results: ALL 216 isolates were unequivocally emm-typable. emm1 was most com mon (18.5%), followed by emm12 (15.7%), emm3 (14.4%) and emm28 (13.9%), Onl y four isolates contained newly validated emm types: emm89 or emm94 were ha rbored by two isolates each. In one isolate, the sequence type s104 was fou nd. Conclusion: Despite an anticipated selective pressure, the prevalence of em m1 among isolates from throat infections in northwestern Germany remains hi gh, but does not reflect the predominance of emm1 among invasive isolates i n Germany.