Gut bacteria can prevent Listeria infection: study

A new study suggests that gut bacteria may hold the key to preventing Listeria infection.

Researchers have identified gut bacteria that could protect against Listeria infection.

Researchers from the Memorial Sloan Kettering Cancer Centre in New York identified four species of gut bacteria that reduced the growth of the bacterium Listeria monocytogenes in mice, but they suggest that much of these beneficial bacteria may be eliminated by antibiotic use.

Study co-leader Simone Becattini and colleagues say that their findings indicate that colonising patients’ guts with the four bacterial species though probiotics could help to stave off Listeria infection.

Symptoms of listeriosis may include headache, fever, diarrhoea, muscle aches, and fatigue. In severe cases, the infection may lead to septicemia, meningitis, and even death.

Listeria infection is most commonly caused by consumption of contaminated dairy products such as soft cheeses, though infection has also been linked to deli meats, melon, and raw sprouts.

The new study suggests that a lack of protective gut bacteria may play a role in greater susceptibility to Listeria infection among these populations.

Becattini and colleagues came to their findings by analysing the gut microbiomes – that is, the population of microorganisms in the gut – in a group of mice treated with antibiotics, as well as mice treated with chemotherapy drugs, and comparing them with those of control mice.

On introducing L monocytogenes to the rodents, the researchers found that those treated with antibiotics showed greater vulnerability to Listeria infection.

They found that the drugs boosted the bacterium’s ability to colonise the gastrointestinal tract and reach the circulatory system, which caused the mice to die.

On further investigation, the researchers identified four species of gut bacteria – all of which were part of the Clostridiales family – that appeared to protect against Listeria infection.

The researchers then tested these probiotic bacteria on L monocytogenes in the laboratory, and they found that they were able to reduce the pathogen’s growth.

Next, the researchers transferred the probiotic bacteria into germ-free mice – that is, mice that possess no microorganisms – and exposed them to L. monocytogenes.

They found that the probiotic bacteria protected the rodents from Listeria infection by reducing the ability of L monocytogenes to colonise the gastrointestinal tract.

“Thus, augmenting colonisation resistance functions in immunocompromised patients by introducing these protective bacterial species might represent a novel clinical approach to prevent L monocytogenes infection,” says Becattini.

 



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