A mouse model of abscess formation is described in which toxic shock syndrome toxin 1 (TSST-1) is produced by Staphylococcus aureus in vivo. Mice injected intravenously with S. aureus developed renal abscesses within 4-7 days. Kidneys excised from infected mice were cultured quantitatively, and extracts from the kidneys were assayed for TSST-1 with use of a competitive enzyme-linked immunosorbent assay. Animals with less than 10(7) S. aureus/g of kidney had less than 6 ng of TSST-1/mL of extract. Toxin levels ranged from less than 6 ng/mL to 271 ng/mL in kidney extracts from mice with greater than 10(7) S. aureus/g of kidney. Urine from infected mice also contained measurable levels of TSST-1 (range, less than 6-728 ng/mL). Mice developed serum antibodies to TSST-1 by 2 weeks after challenge. Serum samples collected 5-7 days after bacterial challenge did not show biochemical changes typical of a toxic shock-like illness in these animals.