Epidemiological markers of group A streptococcal infections in France.

Background & Objectives: A limited number of biotypes, T-types, and emm-types have been found to be associated with invasive isolates of group A streptococci, confirming the involvement of the M protein in virulence and its importance as an epidemiological marker. In this study, the epidemiological markers in the clinical isolates of group A streptococci were compared in invasive and non invasive isolates.

Methods: From 1998 to 2001, 141 invasive and 353 non invasive isolates in France were studied and their biotype, T-type, and emm-type were determined.

Results: The invasive isolates were mostly obtained from blood whereas the non invasive isolates were isolated from throat. Most of the isolates were of biotype 1. The invasive isolates were mostly of the T-type 1 associated with emm-type 1. The T-type 4 associated with emm-type 4 and the T-type 28 associated with emm-type 28 were also frequent. Invasive isolates responsible for puerperal sepsis and non invasive isolates were mostly of the T-type 28 associated with emm-type 28.

Interpretation & Conclusion: This study confirms the high prevalence of isolates of biotype 1, T-type 1, and emm-type 1 among invasive isolates of group A streptococci. The emm-type 28 associated with T-type 28 was frequently observed in non-invasive isolates. A prospective study is being conducted to update the prevalence of the different emm-types in France, which will be of importance for the development of future vaccines.