How these bacteria in chicken guts make us sick

The Campylobacter jejuni bacterium sets up home in chicken intestine. Strategies to prevent infection are hampered by a poor understanding of the complex interactions between the host and the pathogen. (Credit: Leif K-Brooks/Flickr)

The Campylobacter jejuni bacterium is one of the reasons why we are told to make sure our meat, particularly chicken, is cooked properly.

The bug, which lives in chicken intestines, is the most common cause of food poisoning.

If scientists could find a way to block the bacterial molecules that encourage this bug to colonize, it might help prevent the spread of the debilitating illness gastroenteritis.

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Sugar-coated carbohydrates

Researchers at the University of Nottingham have discovered that Campylobacter uses a particular set of sugar-coated bacterial molecules living in the intestinal cell surfaces of the host to colonize and spread.

Professor Dlawer Ala’Aldeen and his team have discovered that the bacteria piggy-back on a set of blood-group antigens (BgAgs) triggered by the host’s cells and use this “free ride” to colonize and spread.

The team identified the exact bacterial molecules that facilitate this host-bacterial cell binding and the sugar-coated carbohydrates that are used to attract the bacteria.

“The molecules are the flagellar protein (FlaA) and the major outer membrane protein (MOMP). The flagella are the locomotion appendages that help the bacterium move and swim around in the gut. MOMP is embedded in the outer layer of the bacterium and forms a channel for internalization of essential nutrients,” says Ala’Aldeen.

“The MOMP is ‘sugar coated’ and it is these ‘glycan decorations’ that are critical for binding BgAgs and the binding to human and chicken intestine.

Jafar Mahdavi, who co-led the study, says they found that “removing a single molecule (Threonine-268) from MOMP significantly reduced the protein’s sugar coating and radically reduced the bacterial ability to bind host cells, cause biofilms in the lab, or colonize chickens in broilers.”

This discovery should help pave the way for the development of new products that can block the binding between Campylobacter and BgAgs, and thereby prevent chicken or human colonization or reduce the burden of raw meat contamination in retail markets.

The Medical Research Council funded the study, which was published in journal Open Biology.

Source: University of Nottingham