Analysis of the Virulence of Uropathogenic Escherichia coli Strain CFT073 in the Murine Urinary Tract

Abstract

This urinary tract infection model was used to monitor the efficacy of a new virulence factor of the uropathogenic Escherichia coli strain CFT073 in vivo. The new virulence factor which we designated TIR-containing protein C (TcpC) blocks Toll-like receptor signaling and the NLRP3 inflammasome signaling cascade by interacting with key components of both pattern recognition receptor systems ( Cirl et al., 2008 ; Waldhuber et al., 2016 ). We infected wild type and knock-out mice with wildtype CFT073 and a mutant CFT073 strain lacking tcpC. This protocol describes how the mice were infected, how CFT073 was prepared and how the infection was monitored. The protocol was derived from our previously published work and allowed us to demonstrate that TcpC is a powerful virulence factor by increasing the bacterial burden of CFT073 in the urine and kidneys. Moreover, TcpC was responsible for the development of kidney abscesses since infection of mice with wildtype but not tcpC-deficient CFT073 mutants caused this complication.

Keywords: Uropathogenic Escherichia coli; Inflammasome; TIR-containing protein C; Toll-like receptor; Urinary tract infection.

Figure 1.. Urine collection in mice.

Place the mouse on a cage metal mesh and hold tail to lift hind legs. Most mice will urinate naturally and urine can be collected in a sterile microcentrifuge tube. Sometimes, using index finger, gentle pressure on abdominal area can be applied to encourage mice to urinate.

Figure 2.. Murine urinary tract infection model.

Image showing the position of the mouse during transurethral catheter insertion.

Figure 3.. Ascending urinary tract infection in mice.

Mice were infected with E. coli CFT073 by intravesical inoculation and sacrificed after 7 days. A. Uninfected control mice show healthy kidney with smooth and round contours, whereas kidney from infected mice displays severe abscess (arrows) formation (B).