FIG 4.

Serotype emm59 GAS strains recovered in the United States are highly virulent in a mouse model of skin and soft tissue infection. (A) Strains MGAS26494, MGAS26495, and MGAS26515 caused large skin lesions in mice. Data are shown as means ± standard errors of the means. (B) Frozen section analysis performed rapidly on specimens collected 72 h postinoculation (day 7 of the study) demonstrates an ulcerated lesion (bracket), severe tissue necrosis (boxed region) and dissemination to the deep and lateral margins (arrows). The images are shown at ×4 original magnification.