Related Experiment Video
Updated: Aug 18, 2026
Establishment and Characterization of UTI and CAUTI in a Mouse Model
Published on: June 23, 2015
Enterococcus faecalis tropism for the kidneys in the urinary tract of C57BL/6J mice
Andrew L Kau1, Steven M Martin, William Lyon
1Department of Molecular Microbiology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8230, Saint Louis, MO 63110-1093, USA.
Abstract:
Enterococcus faecalis is a gram-positive bacterium that can cause a variety of nosocomial infections of which urinary tract infections are the most common. These infections can be exceptionally difficult to treat because of drug resistance of many E. faecalis isolates. Despite their troublesome nature, little is known about the host or bacterial factors necessary for E. faecalis to cause disease in the urinary tract. Using a mouse model of urinary tract infection, we have shown that E. faecalis is capable of persisting in the kidneys of mice for at least 2 weeks. In contrast, bacterial titers from the bladders of the same mice were inconsistent and tended to be much lower than those recovered from the kidney. This preference for the kidney over the bladder is also observed in other clinical E. faecalis strains. Histologic examination of bladder and kidney tissues demonstrated that E. faecalis induced an inflammatory response in the kidney but not in the bladder. This inflammatory response was TLR2 independent and did not induce inflammatory markers typically associated with uropathogenic Escherichia coli. Using a competition assay, we demonstrated that a pyelonephritis clinical isolate had a growth advantage over a laboratory strain of E. faecalis in the kidneys but not in the bladders of mice. Taken together, these results demonstrate that E. faecalis has tropism for the kidneys in the urinary tracts of mice and that this system can be used to study factors involved in the pathogenesis of urinary tract infections.
Insights
Enterococcus faecalis bacteria prefer to infect the kidneys over the bladder during urinary tract infections. This tropism is key to understanding E. faecalis pathogenesis and developing new treatments.
Area of Science:
- Microbiology
- Infectious Diseases
- Immunology
Background:
- Enterococcus faecalis is a common cause of difficult-to-treat nosocomial infections, particularly urinary tract infections (UTIs).
- The specific host and bacterial factors driving E. faecalis UTIs remain poorly understood.
- Drug resistance in E. faecalis complicates treatment strategies.
Purpose of the Study:
- To investigate the tropism of Enterococcus faecalis in a murine model of urinary tract infection.
- To explore the host inflammatory response to E. faecalis in the urinary tract.
- To identify factors influencing E. faecalis colonization and persistence in the kidneys versus the bladder.
Main Methods:
- A mouse model was utilized to establish and track E. faecalis infections in the urinary tract.
- Bacterial titers were quantified in the kidneys and bladders over a 2-week period.
- Histological examination of infected tissues assessed inflammatory responses.
- Competition assays compared the growth advantage of different E. faecalis strains.
Main Results:
- Enterococcus faecalis demonstrated significant persistence in the kidneys, with higher bacterial loads compared to the bladder.
- E. faecalis induced kidney inflammation, distinct from the response seen with uropathogenic E. coli and independent of TLR2.
- A pyelonephritis clinical isolate showed a growth advantage in the kidneys over a laboratory strain.
Conclusions:
- Enterococcus faecalis exhibits a clear tropism for the kidneys in the mouse urinary tract.
- The murine UTI model is suitable for studying E. faecalis pathogenesis and kidney tropism.
- Further research into kidney-specific factors is warranted for understanding and treating E. faecalis UTIs.
