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(CNN) —  

The US Food and Drug Administration approved a new treatment for highly drug-resistant tuberculosis, offering new hope in the fight against the world’s most deadly infectious disease.

TB most affects the lungs and can be particularly difficult to treat. Drug-resistant strains are on the increase due to incomplete and challenging courses of treatment that last for more than 18 months.

Pretomanid, a compound developed by the nonprofit TB Alliance and approved by the FDA on Wednesday, forms part of a three-drug regimen that people can take orally over six months. It treats two drug-resistant strains of the disease, XDR-TB and MDR-TB.

“Until very recently, people infected with highly drug-resistant TB had poor treatment options and a poor prognosis,” said Dr. Francesca Conradie, principal investigator of the trial. “This new regimen provides hope with nine out of 10 patients achieving culture negative status at six months post-treatment with this short, all-oral regimen.”

Tuberculosis claims 4,400 lives a day worldwide. According to the World Health Organization, highly drug-resistant strains account for more than 500,000 of the 10 million new cases of the disease each year and are found in 127 countries around the world.

Scientists tested safety and effectiveness of Pretomanid, which is taken together with bedaquiline – approved as a TB treatment in 2012 – and linezolid, an antibiotic, in patients in South Africa.

Of the 107 patients who were evaluated six months after the end of therapy, 95 (89%) had a successful outcome.

South Africa’s burden of the airborne disease is particularly high, as a high incidence of HIV works with drug-resistant TB, weakening immune systems to make people more susceptible.

“The bacterium that causes tuberculosis can develop resistance to the antibiotics used to treat it. Multidrug-resistant TB and extensively drug-resistant TB are public health threats due to limited treatment options,” FDA Principal Deputy Commissioner Amy Abernethy said in a statement.

Pretomanid is expected to be available in the United States by the end of this year, with the European Medicines Agency and the World Health Organization highly likely to follow suit and approve the treatment.

Pretomanid is only the third new anti-TB drug approved for use by the FDA in more than 40 years.

Treatment of highly drug-resistant TB has traditionally been complex and lengthy, with patients taking a combination of as many as eight antibiotics, some involving daily injections, for 18 months or longer. Some older regimens can cause patients to lose their hearing.

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Dr. Mel Spigelman, president and CEO of TB Alliance, said the new “regimen will hopefully provide a shorter, more easily manageable and highly efficacious treatment for those in need.”

“FDA approval of this treatment represents a victory for the people suffering from these highly drug-resistant forms of the world’s deadliest infectious disease.”