Experts at the universities of Leicester and London have identified that the TB bug lays down body fat that may help it survive passing from one person to another. In the process, the bacteria increase their resistance to anti-TB drugs.

Mike Barer, Professor of Clinical Microbiology at the University of Leicester, said “strenuous efforts were being made to reduce the global burden of tuberculosis, a disease which kills four people every minute”.

“Our success so far has been limited for many reasons; one of these is our failure to control the spread of TB from one person to another. Very little is known about this vital part of the bacterium’s life cycle,” he said. The scientists might be able to identify new therapeutic and preventative targets if they could understand more about the transmission of TB between people.

The Leicester team discovered that, unlike TB bacteria growing in test tubes, many of the bugs in sputum were loaded with fat droplets. These “fat bacilli” were in an inert non-growing state, a condition in which they are more likely to survive the process of passing from one person to another.

The discovery sheds light on the story of “persister bacteria” in TB — a mysterious population believed by many to be the reason why TB patients have to be treated for at least six months. “These surprising findings have opened the door for us to develop new ways to stop TB from spreading and to treat it more effectively,” Barer said.

“We hope that our new ability to monitor these sleepy and resistant bacteria in sputum will enable us to treat the disease more quickly,” he added.

“This work has taken more than 10 years to come to fruition and has taken dedicated work from the teams in Leicester and London. I am particularly delighted for my team in Leicester who fought long and hard to bring this story together,” Barer said.