A drug intended to treat sexually transmitted infections in humans, but lacking immediate need, is showing potential to protect koalas from the disease that is killing them.

Dr Willa Huston of the University of Technology, Sydney, didn’t set out to rescue koalas. Studying the chlamydia bacterium, Huston came across the metabolic inhibitor JO146, which she thought might have promise for fighting the common disease.

Years of research suggested JO146 might be effective. However, antibiotic resistance to chlamydia is not currently as widespread as for diseases such as tuberculosis. With existing drugs still usually effective, there is little interest in spending the large amounts of money required to test a new one's safety.

Huston told IFLScience that at one point she had hoped her work could be applied against other bacterial diseases, but tests on a number of bacteria have not proven promising.

However, humans are far from chlamydia's only victims. In the next lab to Huston, a team was working to save koalas from Chlamydia pecorum, a relative of the Chlamydia trachomatis that infects humans. Koalas' unique digestive system, which allows them to live on eucalyptus leaves poisonous to most other species, are very badly affected by oral antibiotics.

Chlamydia infections can blind koalas and render them infertile, making the disease one of the major causes of their decline. Existing treatments rely on Chloramphenicol 150, a drug no longer being manufactured, with only two year's supply remaining.

^{The effects of Chlamydia infections on koala's eyes can be awful. Willa Huston}

So koala guardians are excited by Huston's publication in Scientific Reports of work showing that JO146 kills C. pecorum without harming koala cells. As an added bonus it also kills C. pneumoniae, another member of the Chlamydia family that also infects koalas.

Hutson's research has been done on tissue samples, not live koalas. “It will be a year or two before we are ready for application,” Huston told IFLScience. “First, we need to trial it on other animals, probably something like a rabbit with a similarly complex gut biome.”

If JO146 proves effective, Huston will face the same problem that has taken Chloramphenicol off the market. “There are only about 100,000 koalas or less,” she told IFLScience. As an Australian icon and a symbol of all that is adorable, koalas attract far more funding than less charismatic beasts, but are still unlikely to make mass production of a drug viable on their own.

Huston is exploring the possibility JO146 will prove effective against species of Chlamydia that infect various other animals, widening the market. Additionally, her plan is to avoid selling JO146 to a corporation, allowing it to be produced on a smaller scale by non-profit bodies.

Meanwhile, Huston pointed out to IFLScience there is “some evidence of treatment failure” for Chlamydia in people. If widespread antibiotic resistance emerges, the existence of an effective treatment for our eucalyptus-loving friends could slash the time it would take to produce a version for humans.

^{Barnarcles the koala recovering after being treated with Chloramphenicol. Unfortunately, with this drug no longer being made regularly, vets are in need of a replacement treatment for koalas against chlamydia. Willa Huston}

[H/T: ABC]