Effect of estradiol treatment on clinical course of Staphylococcus aureus infection. Frequency of arthritis (A), clinical severity of arthritis (B), histologic evaluation of synovitis (C) and erosion (D) of bone and cartilage in joints, as evaluated microscopically. Solid circles, estradiol-treated mice; open circles: placebo-treated mice. Values in B are given as mean ± SEM. Horizontal bars in C and D show median values, and each symbol represents the histologic score for one mouse. Data in A and B are pooled from two separate experiments with 12 to 14 mice per treatment group. *P < 0.05, as analyzed with the Fisher Exact test; ***P < 0.001, as analyzed with regression analysis.