'In the body, immune surveillance cells such as hemocytes (or macrophages in vertebrates) are exposed to a battery of signals from different sources. The cells integrate these signals and react to them accordingly,' he said.

'Once these cells are removed from this complex environment and cultured in a petri dish these signals are lost. Therefore, it is really important to study whole organisms to fully understand how bacteria interact with their host,' added Wood.

Nick Waterfield, study co-author said: 'To be able to film the microscopic battle between single bacterial cells and immune cells in a whole animal and in real time is astounding.

The scientists are hoping to use this system in the future with human pathogens such as Listeria and Trypanosomes, said a University of Bath release.

The study was published in PLoS Pathogens.