Table 4.

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

Isolate source (n)Enzyme activity (101FU)aPb
Mean ± SDMedian
Nonsevere infection (29)1,072 ± 4371,108
Severe infection (48)722 ± 5278770.004
 STSS (17)564 ± 4597040.001
 NF (20)810 ± 5821,1470.079
 STSS + NF (11)804 ± 5091,0560.107
  • 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.