Corneal epithelial cell cytotoxicity after exposure to test strain supernatants over 15, 30, 60, and 90 minutes. (A) IHMA104, IHMA70, as well as the IHMA70 deletion mutants and complementation strains. #P < 3.7e-6 in all instances comparing IHMA104 versus IHMA70. *P < 1.7e-6 in all instances comparing IHMA70Δe1Δe2 versus IHMA70. (B)USA300LAC and corresponding mutant USA300Δkqx and complementation strains. *P < 1.7e-5 for all instances comparing USA300Δkqx versus USA300LAC.