How does Campylobacter cause food poisoning?

Most people have experienced the unpleasant symptoms of food poisoning at some point in their lifetime, and researchers are investigating ways to prevent this from happening. Campylobacter is particularly prevalent, with the World Health Organization stating it is the most common cause of bacterial food poisoning in the world.

Since cattle and poultry carry the bacterium in their guts without suffering any ill effects, this raises the question of how and why it causes food poisoning in humans. Understanding how and why this happens is complicated, but researchers from the University of Georgia (UGA) have discovered that it is down to certain genes.

“Unlike other intestinal pathogens, C. jejuni does not harbour pathogen-defining toxins that explicitly contribute to disease in humans. This makes understanding Campylobacter pathogenesis challenging and supports a broad examination of bacterial factors that contribute to C. jejuni infection,” the study paper stated.

The bacterium has “far-reaching effects” on the global population, causing diarrhoea and severe abdominal cramping, with potentially worse effects on children.

“Campylobacter infections in young children, which can be persistent, are associated with stunted growth periods that can lead to physical and cognitive impairments,” said Alex Crofts, lead author of the study.

These factors encouraged the US Navy Medical Research Center and the Johns Hopkins University Bloomberg School of Public Health to ask citizen volunteers to drink Campylobacter bacteria in a controlled clinical setting. The study aimed to test the effectiveness of new therapies that may protect humans from the infection.

Stephen Trent, Professor of infectious disease in UGA’s College of Veterinary Medicine, built on this study by examining the bacteria in the infectious samples produced by the volunteers, and how it adapts and survives inside human hosts. Trent and his team of researchers suggested they would need to establish the bacteria’s tools for survival in order to work out how to target and kill them.

They found that Campylobacter relied on multiple genes which enable the bacteria to adapt within humans and evade the immune response. Out of over 1500 genes in the bacteria, 11 were linked to persistent infections, particularly cell invasion protein A (cipA).

Published in the journal Nature Microbiology, the team plan to use these results to help design new therapies to treat or prevent Campylobacter infection in the future.

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