Many urinary tract infections (UTIs) can be cleared up with a big bottle of cranberry juice, but when these infections go bad, they can be really, really bad. Uropathogenic E. coli is the leading cause of uncomplicated UTIs, and if left untreated it can proceed right up the urinary tract to the kidneys and sometimes even into the bloodstream. Although the results are usually devastating for patients, the specifics of what E. coli does once it reaches the bloodstream are mostly unknown.
The solution to this problem might just be inside a glowing mouse. In a new study published in mBio, scientists apply a bioluminescent reporter gene in E. coli to learn more about the where and what of the bacterium’s activities during bacteremia. After injecting mice with the bioluminescent strain of uropathogenic E. coli, the researchers used biophotonic imaging – which, incredibly, detects light from the bacteria right through the skin of live mice – to monitor the infection over the next 48 hours. The imaging revealed that E. coli moved all around the mice, but appeared to localize in discrete sites. Comparing these results with infections with various E. coli strains that lacked genes for suspected virulence factors in the blood stream enabled the authors to either confirm or reject the role those genes might play in virulence. The authors speculate that this model of bacteremia could be used to identify other, new bloodstream virulence factors in the future.