Description.
Klebsiella pneumoniae (Kpn) is a significant source of hospital-acquired infections. As Kpn has acquired multi-
drug resistance, it has become even more challenging to treat. Another concern is the increase in isolation of
strains termed as "hypervirulent" Klebsiella pneumoniae or hvKpn known to cause disease manifestations in a
community setting. These isolates have acquired a repertoire of virulence factors, which allow them to cause
disease in immunocompetent individuals. Recently, multiple fatal hospital outbreaks have been linked to multi-
drug resistant hvKpn isolates. Epidemiological studies suggest that gastrointestinal (GI) colonization of hvKpn is
a major reservoir through which it can translocate to sterile sites and cause disease manifestations in the
colonized host. However, hvKpn gut colonization has not been the focus of previous studies as a tractable model
for gastrointestinal (GI) colonization and translocation did not exist. We recently developed a murine model
of Kpn and hvKpn GI colonization, achieved without the requirement of antibiotics. Our tractable model allows
us a better understanding of the dynamic interactions of Kpn with the host with an intact gut microbiome.
Moreover, development of pyogenic liver abscess a trademark of hvKpn infections in humans was also observed
in our GI model of colonization. Thus, we propose that hvKpn uses specific pathways to promote its
translocation, facilitated by its virulence determinants. These determinants can serve as novel targets for the
prevention of the development of the disease state. More recently, with our animal model, we observed
translocation to occur 24 hours post-GI colonization. However, the exact route(s) taken by hvKpn and the role of
specialized enterocytes (M-cells) in translocation remains to be elucidated. Thus, in Aim #1, we will carry out in
vitro cell line assays to determine the pathway(s) taken by hvKpn to promote its translocation. Secondly, we will
determine the host M-cells' role in promoting hvKpn translocation using knockout mice strains. Our data suggest
that hvKpn specific iron acquisition molecule aerobactin (iuc) contributes towards the translocation process.
Even though iuc plays a role in translocation, an iuc mutant does not entirely abrogate it, suggesting that other
factors are critical for translocation. By taking an in vivo novel high-throughput approach in Aim #2, we will
identify putative hvKpn factors that promote its translocation. Results from our studies will not only provide an
understanding of the translocation process but also identify putative translocation determinants, which could be
potential targets to reduce the hvKpn disease burden.