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

Background: Changes in the epidemiology of Streptococcus pyogenes infections may be associated with the introduction and reappearance of individual serotypes within a population. Materials and Methods: Typing of 216 consecutive isolates of S. pyogenes from patients with pharyngitis in the region of Aachen, Germany, was performed by sequencing the emm gene, slide-agglutination of the T-antigen and determining the serum opacity reaction (SOR). Results: ALL 216 isolates were unequivocally emm-typable. emm1 was most common (18.5%), followed by emm12 (15.7%), emm3 (14.4%) and emm28 (13.9%), Only four isolates contained newly validated emm types: emm89 or emm94 were harbored by two isolates each. In one isolate, the sequence type s104 was found. Conclusion: Despite an anticipated selective pressure, the prevalence of emm1 among isolates from throat infections in northwestern Germany remains high, but does not reflect the predominance of emm1 among invasive isolates in Germany.