Novel use of an imaging technique allows researchers to watch bacteria as they colonise the digestive systems of live animals.

In order for gut bacteria to cause disease, they must stick to the host's gut surfaces and invade – a process called colonisation. By unpicking this process, scientists hope to develop treatments to prevent or treat potentially fatal bacterial infections.

Dr Gad Frankel, Dr Siouxsie Wiles and colleagues at Imperial College London are the first to use bioluminescence imaging – where light is emitted in proportion to the number of bacteria present – to explore how Citrobacter rodentium (related to strains of E. coli that cause human disease) colonises the guts of live mice.

Bioluminescence requires oxygen, but as the colonic environment is anaerobic (without oxygen), researchers had previously studied colonisation in harvested organs rather than live animals.

Now, the team has shown that bioluminescence can occur in the colon of live animals as long as the blood supply is intact, suggesting that some oxygen is present in the colon. In vivo use of this technique means that fewer animals are needed for each experiment. Moreover, being able to follow the same animal across the course of a study is an advantage.

Image: Mouse infected with bioluminescent derivative of C. rodentium, before (left) and after exposure to air. From Wiles et al.

External links

• Wiles S et al. In vivo bioluminescence imaging of the murine pathogen Citrobacter rodentium. Infect Immun 2006;74(9):5391–6.