A hollow tube with some culture medium is placed in semi-solid agar inside a bottle. A sample of the bacterium to be tested is inoculated into the medium in the hollow tube and the setup is incubated at 37 °C overnight.
On examining the areas where bacterial growth has occurred there are several observations to be made:
- the colonies of the non-motile bacteria remain confined within the tube at the site of inoculation
- the motile bacteria swim out from the bottom of the tube and colonize the surrounding medium as well
Confirmation may be obtained by subculture and retesting.