The Gram-negative bacteria Campylobacter jejuni is one of the most common causes of food infections, affecting 0.1% - 1% of the European population each year. The consumption of poultry meat products is one of the main sources of infections in humans. PhD Candidate Mahdi Vaezirad has discovered how C. jejuni manages to survive in the intestines of chickens.
The symptoms of a C. Jejuni infection in humans include acute, watery or bloody diarrhoea, stomach pain, fever, nausea and headaches. After a few weeks, the infection can even lead to serious auto-immune diseases, such as Guillain-Barré syndrome. It is therefore vital that research is conducted into how these infections occur, and how the bacteria manage to stay alive in the chickens’ intestines.
Immune system keeps Campyobacter in check
In his PhD research, Mahdi Vaezirad discovered that C. jejuni is adept at adapting to changing circumstances. The bacteria does so by adjusting its metabolism and by actively changing the environment in the intestines or the biology of the host cell. “The importance of the chicken’s immune system in keeping Campylobacter in check became clear after we weakened the immune system by administering glucocorticoid. A healthy chicken simply can’t get sick from the bacteria.”
C. jejuni adjusts the micro-environment
“We also discovered that the metabolism of Campylobacter influences the pH levels of the micro-environment”, Vaezirad adds. “That allows Campylobacter to create the optimal circumstances for growth, allowing it to multiply rapidly. It also reduces the need for individual bacteria to constantly adjust to less optimal growth circumstances. That saves it a lot of energy.”
Vaezirad also discovered that Campylobacter is able to actively inhibit infection by neutralising the host’s harmful products. This allows the bacteria to avoid the host’s immune system more effectively. The discovery of these methods that Campylobacter uses to survive in the host presents new opportunities to deal with these mechanisms in the future.