Nonhemolytic Streptococcus pyogenes isolates that lack large regions of the sag operon mediating streptolysin S production.

Among nonhemolytic Streptococcus pyogenes (group A streptococcus) strains (n = 9) isolated from patients with pharyngitis or acute otitis media, we identified three deletions in the region from the epf gene, encoding the extracellular matrix binding protein, to the sag operon, mediating streptolysin S production.