Armour for good bacteria against antibiotics
Genetically engineered probiotic protects the gut microbiome and reduces likelihood of antibiotic resistance spreading.
Researchers of synthetic biology based at the Massachusetts Institute of Technology (MIT) in the US have devised a system to protect the gut microbiome from the effects of antibiotics.
The new study, published in Nature Biomedical Engineering,
reports on the successful use in mice of a “live biotherapeutic” – a genetically engineered bacterium that produces an enzyme which breaks down antibiotics in the gut.
Antibiotics are hugely important in fighting bacterial infections, but increasing human use of them has contributed to the rise of antibiotic resistance, which has made many bacterial diseases increasingly difficult to successfully treat.
Antibiotic treatment can also kill off bacteria in our resident healthy gut microbiome – the trillions of microbes that live in our gastrointestinal tract and assist with food digestion, immune development and vitamin synthesis.
In some cases, these indiscriminate effects of antibiotics can have lifethreatening consequences. In the US, about 15,000 deaths each year are attributed to diarrhoea and colitis (inflammation of the colon) caused by overgrowth of the bacterium Clostridium
difficile following antibiotic overuse.
The team from MIT began with a strain of the bacterial species Lactococcus lactis, which is typically used in cheese production and considered generally safe for human consumption.
The researchers genetically engineered the L. lactis strain to produce an enzyme called betalactamase, which breaks down beta-lactam antibiotics. Betalactams are a class of widely used antibiotics including penicillin, ampicillin and amoxicillin. They currently account for about 60% of the antibiotics prescribed in the US.
To test their invention, they gave mice an injection of ampicillin as well as two oral doses of engineered L. lactis.
They showed that the L. lactis successfully produced betalactamase and degraded the ampicillin in the mouse gut, without reducing the levels of ampicillin in the blood.
“This work shows that synthetic biology can be harnessed to create a new class of engineered therapeutics for reducing the adverse effects of antibiotics,” says the paper’s senior author, James Collins.