Researchers discover new method of mapping how bacteria spread within the body

Researchers at the University of Cambridge have discovered a new, more accurate, method of mapping how bacteria spread within the body, a breakthrough that could lead to more effective treatments and prevention of certain bacterial infections.

Dr. Pietro Mastroeni, Professor Duncan Maskell at the Centre for Veterinary Science, and their teams have pioneered the integration of mathematical models with observational data to predict the spread of individual bacteria within the human body. Their findings are reported in the November issue of PLoS Biology.

The work analyses the spread and distribution of Salmonella in the body, which is a bacterium that causes typhoid fever and food borne gastroenteritis in humans and animals, with severe medical and veterinary consequences and threats for the food industry. The work is of broad significance as these novel research approaches are applicable to a multitude of pathogenic microorganisms.

These studies indicate that individual bacteria and their progenies cleverly escape from host cells and distribute to new sites of the body, continuously staying one step ahead of the immune response. The type of spread varies between different bacteria, thus posing challenges for the rational treatment or prevention of these infections.

Some antibiotics and vaccines are better at killing bacteria outside of the cells; others are more effective at killing infections within the cells. By understanding where bacterial pathogens hide in the body and how they spread through the body's tissues, doctors will be able to decide the most effective antibiotics or vaccines to treat and prevent various types of infection.

Dr. Mastroeni said, "The fight against bacterial infections is analogous to fighting a battle, if you know where your enemy is and how it moves around, you can make calculated, strategic strikes."

Currently, the debate over the usefulness of multiple-drug therapy must take into account the full evaluation of potential synergistic effects of combining drugs that can target bacteria in different body compartments. Furthermore, drug resistance can be caused, in part, by improper "blanket" use of antibiotics. As Dr. Mastroeni's more precise predictions will lead to the refined use of antibiotics, it will enable the medical field to devise more targeted treatments and to more effectively manage antibiotic drug resistance.

In the past, similar investigations have been hampered by the difficulty of identifying and observing directly the infection process within live tissues. For this study, the Cambridge researchers used advanced fluorescence microscopy techniques to observe intracellular growth of Salmonella bacteria within living cells.