Dr. Rosen evaluates children on the Infectious Diseases service at St. Louis Children's Hospital. In the research lab, he studies basic pathogenic mechanisms of Klebsiella pneumoniae. This organism often carries sets of genes that render it resistant to most, if not all, antibiotics available. Klebsiella, and other carbapenem-resistant Enterobacteriaceae (CRE), have recently been assigned a threat level of urgent by the CDC. Utilizing mouse models of pneumonia and urinary tract infection, Dr. Rosen dissects mechanisms by which Klebsiella pneumoniae infects the host. Specific interests includes differential regulation of virulence determinants, including type 1 pili and capsule, and adaptive immune responses to Klebsiella in the lung. The ultimate goal is to develop further understanding of Klebsiella pneumoniae pathogenesis, which may reveal alternative therapies to combat these resistant organisms.