Detection of TSST-1 and SEB in supernatants from clinical S aureus isolates and expression of B1Rs and B2Rs in a patient suffering from an S aureus soft-tissue infection. (A-B) Supernatants from the clinical isolates 9730, 1878, 2374, 1024, and 15159 (lane 2 to 6) were separated on SDS-PAGE, transferred onto nitrocellulose membranes, and immunostained with antibodies against TSST-1 (A) or SEB (B). The strain ATCC 700699, whose genome has been completely sequenced, was used as a control (lane 1). Note that the apparent molecular weights of toxins vary between the tested strains. Size variation is a common feature of bacterial proteins from different strains that is often caused by homologous recombination between repeated regions within the gene³⁹  and has normally no influence on the activity of the protein. (C) Tissue biopsies from the epicenter of the infection site and from a distal site were obtained from a patient with a soft-tissue infection caused by S aureus. The biopsies were cryosectioned and immunohistochemically stained for IL-1β, B1R, and B2R. Omission of the primary antibody was included as a negative control and was always completely negative. Stainings were quantified by in situ imaging and the results are presented as the imaging value: area and intensity of the positive stain (brown) in relation to the total cell area (blue), as previously described.²⁶