DETECTION AND NUCLEOTIDE-SEQUENCE ANALYSIS OF THE SPEC GENE IN SWEDISH CLINICAL GROUP A STREPTOCOCCAL ISOLATES

The production of pyrogenic exotoxins SpeA, SpeB, and SpeC by group A streptococci has been associated with streptococcal toxic shock syndro me. Several epidemiological studies using DNA hybridization and PCR an alysis have been performed in attempts to correlate one or several of the toxins with streptococcal toxic shock syndrome. The results reveal great variation in the occurrence of the speA and speC genes among cl inical isolates. In this study we show that the speC gene could be det ected by nested PCR in five Swedish T1M1 strains isolated from patient s infected with group A streptococci as well as in three Norwegian T1M 1 isolates, previously reported to lack speC as determined by dot blot hybridization. To verify the identities of the amplified products, th e nucleotide sequences of the PCR fragments from one Swedish T1M1 stra in and from the toxin reference strain NY5 were determined. The nucleo tide sequences showed that the amplified products were speC and of all ele type C2, on the basis of the nucleotides in positions 438 and 456. However, one additional base pair substitution was found in NY5 at po sition 147 and in the Swedish isolate at position 157 which resulted i n nonsynonymous amino acid changes. Thus, these speC genes represent t wo new allelic variants.