Analysis of acquisition of Pseudomonas aeruginosa gastrointestinal mucosal colonization and horizontal transmission in a murine model.

BACKGROUND Laboratory systems to study bacterial transmission and mucosal colonization leading to infection have not been utilized. METHODS We determined whether transmission of various strains of Pseudomonas aeruginosa among individual mice could occur and investigated the properties of such strains in establishing gastrointestinal (GI) mucosal colonization as well as in disseminating systemically after induction of neutropenia. RESULTS P. aeruginosa isolates associated with epidemic spread among patients with cystic fibrosis (CF) readily established GI colonization at higher levels than did strains associated with acute infections in patients without CF, and they outcompeted these strains. Colonization was associated with resistance to bile salts. However, epidemic CF isolates did not disseminate after induction of neutropenia and did not induce as much mucosal pathology as did strains that were capable of disseminating. CONCLUSION Murine models can be used to study P. aeruginosa transmission and early colonization, and the properties of these strains associated with their known clinical behaviors are mimicked in this setting.