FIG. 2.

Relative heat distribution in 20 repeated measurements of the reference strains MSSA ATCC 29213 and MRSA COL (A); and 30 clinical isolates, 10 different MSSA and 20 different MRSA strains (B). Relative heat is calculated as the ratio between the total heat in the presence and absence of 4 μg/ml cefoxitin after 3 h, 4 h, and 5 h of incubation. Open circles indicate MSSA and closed circles MRSA; the horizontal line indicates the cutoff value of relative heat (0.4) used for the discrimination of MSSA and MRSA.