The Cotton Rat as a Model for Staphylococcus aureus 19 Nasal Colonization in Humans

Staphylococcus aureus nasal colonization is a well-known risk factor for development of S.aureus infections in humans, but despite this established association, we are only beginning to understand the factors, both host and pathogen, that play a role in the colonization of the nares by S. aureus. The cotton rat is a model for many human respiratory pathogens and has proved its utility as a robust model for S. aureus nasal colonization. In this animal model, S. aureus is instilled in the nostrils of adult cotton rats, the bacteria rapidly colonize, and 7 days later S. aureus nasal colonization is enumerated by surgical removal of the nose and recovery of the colonizing S. aureus. This model is an excellent animal model to allow for the evaluation of the efficacy of various therapies, including semi-solid formulations, for determination of their ability to eradicate S. aureus nasal colonization. Further, the cotton rat model allows for assessment of the ability of defined genetic mutants of S. aureus to colonize mucosal surfaces. Finally, this model has demonstrated its utility for the assessment of various antigens as vaccine candidates to protect against S. aureus nasal colonization. This chapter will discuss in detail the method to establish nasal colonization, treatment and eradication of colonization, and recovery of the colonizing bacteria from the nose.