Table 1.

Characteristics of cutaneous lesions identified in SKH1 mice inoculated with the GAS M3 wild-type strain or cysteine protease mutanta

Skin location and lesion characterNo. positive/total at the following time (h) and treatment:
244872
PBS controlWild-type strainProtease mutantPBS controlWild-type strainProtease mutantPBS controlWild-type strainProtease mutant
Epidermis, infarction0/60/60/60/65/60/60/66/61/6b
Dermis
 Suppurative inflammation0/64/65/62/66/65/62/66/66/6
 Collagen necrosis0/61/61/61/65/61/60/60/6d 0/6
 Extension through panniculus0/62/62/60/65/61/60/66/61/6b
 Bacterial colonies away from inoculation site0/61/60/60/65/61/60/64/60/6b
Subcutis
 Single abscess0/63/66/60/64/66/60/60/64/6c
 Multiple abscesses0/63/60/60/62/60/60/66/60/6c
 Extension to underlying muscle0/64/65/60/66/64/60/66/66/6
 Suppurative inflammation0/66/66/62/66/65/60/66/66/6
 Perineural PMNs/necrosis0/62/61/60/61/60/60/64/62/6
Muscle, necrotizing myositis0/63/63/60/66/64/60/63/66/6
  • a Mice were randomly assigned to be inoculated with the GAS M3 wild-type strain or cysteine protease mutant or with PBS. The statistical difference between cutaneous lesions in animals (days 2 and 3 combined) inoculated with the wild-type or cysteine protease mutant strain was calculated by using Fisher’s exact (two-tailed) test.

  • b P < 0.01.

  • c P < 0.05.

  • d Collagen necrosis in the dermis on day 3 was masked by the increased size of infarcts.