Molecular subtyping of prevalent M serotypes of Streptococcus pyogenes causing invasive disease

Abstract

Reproducible methodologies and a scheme for high-resolution genotyping of Streptococcus pyogenes were defined with respect to a study of six predominant M serotypes causing invasive group A streptococcal disease in the United Kingdom. Serotype reference strains were compared with nine clinical isolates of each serotype from patients with diseases such as pneumonia, puerperal sepsis, toxic shock-like-syndrome, cellulitis, or necrotizing fasciitis. Four enzymes were evaluated for their discriminatory power in 16S rRNA gene-specific ribotyping. Discriminatory power was greatest with EcoRI, which generated serotype-specific ribotypes, and with SacI, which could subdivide strains of the same M serotype. Twenty-five combined ribotypes were found among the 60 strains, and the indices of discriminatory power (D values) of this method varied from 0.51 within serotype M1 to 0.98 within strains of serotype M5. Macrorestriction with the rarely cutting endonuclease SmaI and pulsed-field gel electrophoresis gave D values varying from 0.37 within serotype M1 to the maximal 1.0 within serotype M5. Comparison of macrorestriction profiles revealed various degrees of genetic heterogeneity within M serotypes. Strains of M1, M3, M6, and M11 exhibited clonally related macrorestriction profiles, while those of R28 and M5 strains were consistent with polyphyletic origin.

Positive correlation between low adhesion of group AStreptococcusto mammalian cells and virulence in a mouse model

“…When we analyzed the GAS isolates used in this study by PFGE after SmaI digestion, we found that their PFGE patterns agreed with those reported previously (Stanley et al , 1995; Murase et al , 1999) (Fig. 1).…”

A locus of group A streptococcus involved in invasive disease and DNA transfer

“…The emergence of exceptionally virulent strains of these serotypes (Musser et al ., 1991;Cleary et al ., 1992;Musser et al ., 1995) suggested that the increased virulence might be associated with specific genetic elements that could be acquired by horizontal transmission, but no such evidence has been provided. Other studies demonstrated that additional serotypes caused invasive infections (Norgren et al ., 1992;Stanley et al ., 1995;Chaussee et al ., 1996;Cockerill et al ., 1997;Muotiala et al ., 1997). Furthermore, © 2002 Blackwell Publishing Ltd, Molecular Microbiology , 46 , 87-99 the clonal M1T1 strains could be isolated from patients with severe and non-severe invasive infections (Chatellier et al ., 2000).…”

Characteristics of Streptococcus pyogenes Serotype M1 and M3 Isolates from Patients in Japan from 1981 to 1997

“…In this study, we compared S. pyogenes strains obtained from patients with pharyngitis to those obtained from patients who were asymptomatic over a 7-to 8-year interval. Strain comparisons were performed by using PFGE with SmaI-digested (15) and SfiI-digested (7) chromosomal DNA; PCR-detected speA, speB, or speC genes (11); and biotyping with a commercial biochemical test kit (Rapid ID 32 Strep; bioMeriuex, Marcy-l'Etoile, France) (1). Numerical analysis of SmaI-digested patterns was performed by identifying the proportion of fragments shared by pairs of isolates by the method of Nei and Li (9) (also known as the Dice coefficient of similarity) and calculated as F ϭ 2n xy /(n x ϩ n y ), where n x and n y are the total numbers of fragments from isolates x and y, respectively, and n xy is the number of fragments identical in the two isolates.…”