‘Bacterial soldiers’ against tuberculosis?


While everyone is watching COVID-19, another lung infection continues to take its toll: tuberculosis. Dr Anandi Martin, a visiting researcher at UCLouvain, is interested in bacteriocins. These bacterial ‘soldiers’ could act in place of or in addition to the antibiotics to which tuberculosis is increasingly resistant.

A quarter of the world's population is infected with Koch’s bacillus, the bacteria responsible for tuberculosis. The vast majority will never have any symptoms, in whom the tuberculosis is said to be latent. But about 10% of those infected will develop the disease. According to the latest report on the subject by the World Health Organization (WHO), there are 10 million tuberculosis patients in the world.

(Very) long treatments!

Treatments for tuberculosis exist. ‘For simple forms of the disease, the patient must take antibiotics for six months,’ says Dr Martin, a tuberculosis specialist who is visiting the Centre for Applied Molecular Technologies headed by Prof. Jean-Luc Gala. ‘And in the case of multidrug-resistant strains, it takes two years of treatment, with potentially severe side effects. Many patients find it difficult to take their medication properly. Then there’s the emergence of tuberculosis strains that are extremely resistant to almost all known drugs [1]The result, again according to WHO, is that approximately 1.2 million people died of tuberculosis in 2019. This is more than those who died of AIDS [2].

Rediscovering bacteriocins

Since March 2020, Dr Martin has been a researcher at Syngulon. Her laboratory research, however, is still carried out in the Centre for Applied Molecular Technologies (CTMA) laboratory of the UCLouvain Institute for Experimental and Clinical Research (IREC), which has established partnerships with this Liège ‘start-up in the labs’ [3] specialising in synthetic biology. In particular, it produces bacteriocins. ‘Bacteriocins are peptides, small molecules produced by most bacteria to defend themselves,’ Dr Martin explains. ‘Each bacterium has its small army of bacteriocins that are toxic to other bacteria in their environment.

Bacteriocins have been known for a long time. They were discovered in 1925 by the Belgian microbiologist André Gratia. Three years later, Alexander Flemming discovered penicillin, marking the start of the glorious reign of antibiotics. The antimicrobial virtues of bacteriocins then fell into oblivion. But in recent years, faced with the rise of antimicrobial resistance, bacteriocins have attracted new interest in the scientific community.

Testing a catalogue of bacteriocins

We have a collection unique in the world of around 300 bacteriocins,’ Dr Martin says. ‘I’m responsible for testing them on tuberculosis. The goal is to find out whether one or more bacteriocins – possibly in combination with an antibiotic – could act against Koch’s bacillus and fight tuberculosis caused by germs resistant to the current pharmaceutical arsenal.’

Koch’s bacillus is in the genus called mycobacteria, which have a very thick outer membrane that antibiotics often have a hard time crossing. Perhaps there are bacteriocins that could weaken the wall of Koch’s bacillus? To find out, Dr Martin began to study the scientific literature in order to identify promising bacteriocins. ‘Our bioinformatics tools should also help us find new bacteriocins that could be of interest regarding infectious diseases like tuberculosis. And as soon as the confinement imposed by COVID-19 is completed, I’ll launch the first in vitro tests.’ 

And against COVID-19?

In the current circumstances, it’s hard to talk about respiratory infections without mentioning COVID-19. Despite their similarities (see box), tuberculosis and COVID-19 are two different diseases. That said, Dr Martin is taking advantage of her review of the scientific literature to look at certain bacteriocins with antiviral properties. ‘There's also a whole scientific discussion about the BCG vaccine,’ she adds. ‘This vaccine protects children from certain severe forms of tuberculosis. And we know that, by stimulating the immune system, the BCG vaccine also has protective effects against other respiratory diseases. Studies have therefore just started to inquire whether the protective effect of the BCG vaccine extends to COVID-19.’ Expect a verdict in the coming months.

What do COVID-19 and tuberculosis have in common?

While there’s a fundamental difference between the two diseases – tuberculosis is caused by bacteria while COVID-19 is caused by a virus – they have some similarities.

  • They’re respiratory diseases, thus attack mainly the lungs.
  • They’re transmitted by aerosol: the dispersion of infected fine droplets when an infected person coughs or sneezes
  • They’re highly contagious; infected persons must be quarantined.
  • Cough and persistent fever are common symptoms, but the majority of infected persons are asymptomatic.

Candice Leblanc

[1] Of the world’s 10 million tuberculosis patients, 500,000, or 5%, suffer from antibiotic-resistant tuberculosis.
[2] According to WHO, 1.1 million people died of AIDS in 2019.
[3] A ‘start-up in the labs’ doesn’t have its own laboratory and works in close collaboration with partner university laboratories.

A glance at Anandi Martin's bio

Anandi Martin is a researcher in biology and specialist in tuberculosis. She holds a master's degree in biology and a certificate in education and public health obtained in 1992 and 1996 respectively from the University of Liège. During this time she became interested in tuberculosis and devoted her PhD to it, becoming a doctor of biochemistry in 2006 at Ghent University. She has participated in several research programmes in universities (Institute of Tropical Medicine in Antwerp, Ghent University, etc.) and international organisations (World Health Organization, European Commission, Doctors without Borders, Damien Foundation, etc.). She joined the UCLouvain Medical Microbiology Centre in 2016. Since March 2020, she has been working for the start-up Syngulon in collaboration with the UCLouvain Centre for Applied Molecular Technologies (CTMA), supported by the Walloon Region.

Published on April 30, 2020