FIG 2.

sfb-negative mice acquire increased resistance to S. aureus pneumonia after cohousing with sfb-positive mice. Female sfb-negative C57BL/6 mice and age-matched, female, sfb-positive C57BL/6 mice were housed together in isolated cages for 2 weeks prior to bacterial challenge. All of the cohoused mice were sfb positive at the time of bacterial challenge. Eight additional sfb-negative or sfb-positive mice were not cohoused for the same period and remained sfb negative or sfb positive, respectively. After 2 weeks, mice were challenged with 5 × 10⁸ CFU of MRSA i.n. and sacrificed after 18 h for determination of the number of bacterial CFU per gram of lung tissue. Symbols represent individual animals, and horizontal bars represent the medians. P values were determined by the Kruskal-Wallis test (overall ANOVA; P < 0.01), and P values depict Dunn's multiple pairwise comparisons for nonparametric distributions. ns, not significant.