Table 5.

Cysteine protease activities in culture supernatants of SpeB-positive GAS isolated from invasive cases of varying severity

Isolate source (n)Enzyme activity (101FU)aPb
Mean ± SDMedian
Nonsevere infection (25)1,212 ± 471,140
Severe infection (32)1,054 ± 46.81,1480.023
 STSS (10)908 ± 61.18770.001
 NF (13)1,216 ± 34.61,2000.950
 STSS + NF (9)982 ± 118.71,0800.037
  • a The enzyme activity of SpeB was determined by a fluorescent enzyme assay described in Materials and Methods.

  • b Differences between the enzyme activities of SpeB produced by isolates from nonsevere cases and isolates from various subgroups of severe cases were evaluated by the Studentt test.