Like so many other diseases, tuberculosis is becoming increasingly resistant to treatment by antibiotics. There may be hope, however, as scientists have developed a new vitamin-based treatment which could both halt the disease, and prevent antibiotic-resistance from developing further.

According to a World Health Organization estimate, in 2017 there were approximately 558,000 cases worldwide in which the most effective first-line antibiotic wasn't effective at treating tuberculosis. Out of those cases, about 82 percent were also resistant to multiple other types of antibiotics.

With that in mind, a multi-center team led by the Royal College of Surgeons in Ireland looked to a vitamin A derivative known as all trans retinoic acid (atRA). Previous studies had shown that it was effective at killing tuberculosis-causing bacteria, which get inhaled into the lungs within water droplets.

Utilizing a spray-drying process, the scientists encapsulated atRA within microparticles made from a biocompatible/biodegradable polymer called poly(lactic-co-glycolic acid). Those particles are small enough that they could safely be administered using an inhaler.

In lab tests performed on mice infected with Mycobacterium tuberculosis bacteria, just three inhaled microparticle treatments were found to substantially reduce bacterial populations in the lungs, and to reduce associated lung damage. It is hoped that once developed further, the medication could enter human clinical trials.

"Many cases of TB are now becoming resistant to existing antibiotics," says Prof. Sally-Ann Cryan, one of two lead scientists. "This new treatment could be used alongside antibiotics to treat drug-resistant TB and also possibly reduce the rate of antibiotic resistance resulting from conventional antibiotic treatments."

A paper on the research – which also involved scientists from St. James Hospital (Dublin), Trinity College Dublin and Imperial College London – was recently published in the European Journal of Pharmaceutics and Biopharmaceutics.