FIG 1.

sfb-negative mice exhibit increased susceptibility to MRSA pneumonia compared to sfb-positive mice. C57BL/6 mice from The Jackson Laboratory (sfb negative) and Taconic Biosciences (sfb positive) were challenged with 5 × 10⁸ CFU of MRSA intranasally and sacrificed after 18 h for determination of the number of bacterial CFU per gram of lung (A) or spleen (B) tissue. Symbols represent individual animals, and horizontal bars represent the medians. P values were determined by the Mann-Whitney U test. The histological appearance of lung tissue is shown for representative sfb-negative (C and D) and sfb-positive (E and F) mice 18 h after infection with MRSA Lac. The sfb-negative mice showed higher percentages of lung tissue involved in inflammation (60% affected [C and D] versus 10% affected [E and F]). Magnification, ×40 (C and E) or ×100 (D and F). Bars, 1 mm.