Distribution of group A streptococcal virulence genes in group C and G streptococci

Streptococcus dysgalactiae, subsp. equisimilis elicit a range of clinical manifestations similar to that of their close genetic relatives, group A streptococcus (GAS). The similarity in disease profiles raises questions as to the degree of genetic similarity between these two human pathogens, particularly in relation to virulence gene repertoires. In this study, we use a group A streptococcal virulence array comprising of 60 genes previously described as GAS virulence factors, and another 159 genes predicted to encode for extracellular proteins to examine the extent of their occurrence in 58 S. dysgalactiae subsp. equisimilis isolates. Between 25% and 50% of the genes represented on the array were present in the S. dysgalactiae subsp. equisimilis isolates. These observations highlight the similar virulence attributes of closely related human pathogenic streptococci.