Staphylococcus aureus Infection in Humanized Mice: A New Model to Study Pathogenicity Associated With Human Immune Response.

BACKGROUND Staphylococcus aureus is a common pathogen among humans worldwide, with an increasing prevalence of multidrug resistance. The understanding of virulence factors inducing pathogenicity is still incomplete, and thus far the transfer of results from animal studies into successful clinical trials has been difficult. METHODS In this study, we established an S. aureus infection model in mice engrafted with a human immune system, compared it with infected wild-type and nonhumanized mice, and investigated pathogenesis in these models. RESULTS Staphylococcus aureus infection was aggravated in humanized mice, compared with wild-type or nonengrafted mice. The humanized mice displayed a significantly reduced survival percentage, increased weight loss, and a more-rapid increase in bacterial burden. In addition, S. aureus infection induced T-cell activation, apoptosis, and Fas receptor expression in humanized but not wild-type mice. CONCLUSIONS Our findings demonstrate the different pathogenetic mechanisms in wild-type and humanized mice and the possible benefit of including humanized mice in future studies involving S. aureus as a prior step to human clinical trials.