Campylobacter jejuni

Campylobacter jejuni facts for higher education

Campylobacter jejuni

Campylobacter are a genus of Gram-negative bacterium. They are can grow in low oxygen conditions such as the gut, are oxidase positive and typically spiral shaped.

Campylobacter jejuni and the closely related species Campylobacter coli are the main bacterial species responsible for incidents of food poisoning in the UK, and the rest of the developed world. C. jejuni is so widely implicated in food poisoning - usually resulting in gastroenteritis - because it has formed a mutually harmless relationship with chickens and other birds. It is found living in the guts of the majority of chickens reared for food and is easily transferred onto meat sold for food. As a result most fresh meat from factory farmed chicken, free range or organic chickens contains C. jejuni (a survey in 2007/2008 showed that Campylobacter was present on 65% of fresh chicken samples). Although it is easily killed by proper cooking, poor hygiene in the kitchen can easily transfer the bacteria from raw chicken onto plates, cutlery or uncooked ingredients. This is why it is important to wash your hands after handling raw chicken and to never use the same chopping board for meat and vegetables.

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Scanning electron microscope image of C. jejuni
This false colour image shows the characteristic corkscrew shape of C. jejuni and the flagella (coloured in brown on this image) extending from both ends of each bacterium. (Photo by De Wood; digital colourization by Chris Pooley. Image taken from the Agricultural Research Service).

While gasteroenteritis is unpleasant in its own right what makes food poisoning by C. jejuni particularly worrisome is that in a small number of cases patients go on to develop a condition called Guillain–Barré syndrome (GBS). Although the actual rate of this occurrence is low (fewer than 1 in 5000 campylobacterosis patients develop GBS) because hundreds of thousands of people are affected each year this translates to a significant number of cases. GBS typically occurs two to three weeks after the initial illness and is marked by flaccid paralysis - that is the patient loses the ability to control their body and their muscles become completely relaxed. The initial symptoms are weakness or tingling sensations in the legs which can spread to the arms and upper body and in severe cases to the whole body. Providing the patient can be taken to hospital where they can be maintained by artificial respiration most recover completely over the following months although lasting disability occurs in 20% of cases, with severe disability occurring in 5-10% of cases. The disease is fatal in 2-3% of patients even with complete access to modern medicine. Further information on Guillain barre syndrome can be found on our dedicated, higher education page.

  • One key virulence determinant of Campylobacter jejuni that is particularly interesting and is a focus of the research at Leicester, is it's flagellar motility.
  • Many genes in C.jejuni including genes involved in flagellar motility are subject to a process known as phase variation. Phase variation is the switching on/off of genes in response to mutation and is a key factor in the bacteria's ability to cause disease.

An excellent review on the molecular biology of C. jejuni can be found here.

Campylobacter jejuni...
• Commonly found in poultry.
• It is the leading cause of food poisoning in the developed world.
• In a small number of cases C. jejuni infection leads to Guillain-Barré syndrome - a flaccid, full-body paralysis

 

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