Detection of pyrogenic exotoxin SpeA, SpeB and SpeC genes in Chilean streptococci isolates and their association with clinical manifestations

Background: The virulence of Streptococcus pyogenes is determined by a vari ety of structural molecules, toxins and complex enzymes. Pyrogenic exotoxin s cause fever, erythematous reactions, cytotoxic and immunological effects. Aim: To assess the frequency of speA, SpeB and SpeC genes in Chilean Strep tococcus pyogenes strains and their association with the invasiveness of in fections. Material and methods: The genes for 114 strains of group A Strept ococcus pyogenes isolated from Chilean patients with invasive or non invasi ve infections. Results: The gene for SpeA was present in 30.7% of isolates, the gene for SpeB was present in 69.3% and the gen for SpeC in 44.7% of is olates. The gene for SpeA was present in 20 of 33 invasive infections and i n 15 of 81 non invasive infections (p <0.0001). On the contrary, the gene f or SpeC was present in 11 of 33 invasive infections and in 41 of 81 non inv asive infections (p <0.05). The frequency of speB was similar in invasive a nd non invasive infections. Conclusions: There is a clear relationship betw een the presence of SpeA genes and the severity of infections caused by Str eptococcus pyogenes.