TABLE 1.

Comparison of in vivo virulence of cytotoxic and noncytotoxic S. aureus

S. aureus strainTime until death (days)aNo. dead/total no. at an ID of 108 CFUb (%)No. with arthritis/total no. at an ID of 106 CFUc (%)
Cytotoxic isolates
    ATCC 292131, 1, 1, 1, 1, 1, 17/76/7
    K421, 1, 1, 14/44/4
    K441, 1, 1, 14/42/4
    K501, 1, 1, 14/42/4
    K511, 1, 2, >143/43/4
    Total22/23 (96)*d17/23 (73)**
Noncytotoxic isolates
    K1352, >14, >14, >14, >141/50/5
    K622, 3, 43/31/3
    K631, >14, >141/30/3
    K531, 3, 43/31/3
    K641, 2, >142/31/3
    DU1090 WT1, >14, >14, >14, >141/51/5
    DU1090 H35R>14, >14, >14, >14, >140/51/5
    Total11/27 (41)*5/27 (19)**
  • a Results represent the time until death of each individual mice infected i.v. with 108 CFU of either cytotoxic or noncytotoxic S. aureus isolates.

  • b Frequency of lethality in groups of mice challenged with cytotoxic and noncytotoxic S. aureus isolates. ID, infectious dose.

  • c Results represent arthritis frequencies and the total number of mice challenged with 106 CFU of either cytotoxic or noncytotoxic S. aureus isolates. ID, infectious dose.

  • d For values indicated by * and **, P < 0.01 for the overall difference between the indicated groups.