Complementation of a speA negative Streptococcus pyogenes with speA - effects on virulence and production of streptococcal pyrogenic exotoxin A

We have shown previously that an isogenic SPEA-negative Streptococcus pyoge nes strain did not attenuate virulence in a murine model of necrotizing fas ciitis. The aim of this study was to confirm that streptococcal pyrogenic e xotoxin A (SPEA) is not crucial for streptococcal invasiveness in murine in vasive infection. The SPEA-negative S. pyogenes (H326) was complemented wit h SPeA extra-chromosomally to create strain H361 which produced 2.2-fold mo re SPEA compared with the parental speA(+) wild-type (H305). The growth pha se-regulated expression of SPEA in vitro was unaffected in this strain. Com plementation with speA resulted in reduced virulence and bacterial counts i n invasive murine infection. SPEA production was quantitated from muscle ti ssue of infected mice. However, H361 did not produce more SPEA than H305 in vivo. We conclude that SPEA does not play a key role in invasive murine st reptococcal infection. (C) 2001 Academic Press.