The World Health Organization on Thursday recommended a speedier, cheaper treatment plan for patients with superbug forms of tuberculosis (TB) - a change that should help cure thousands of the killer disease.

In what the WHO's leading TB expert said was a critical step forward in tackling the "public health crisis" of multi drug-resistant tuberculosis (MDR-TB), the Geneva-based health agency said the new treatment plan could now be completed in 9-12 months rather than the two years previously recommended.

The shorter treatment regimen also costs significantly less - at just under $1,000 per patient in developing countries, said Mario Raviglione, director of the WHO's global TB program.

"The new WHO recommendations offer hope to hundreds of thousands of MDR-TB patients who can now benefit from a test that quickly identifies eligibility for the shorter regimen, and then complete treatment in half the time and at nearly half the cost," he said in a statement.

Multi drug-resistant TB is caused by TB bacteria that are resistant to at least the two most effective drugs, isoniazid and rifampicin, and possibly others too.

Based on figures from 2014, the latest year for which data are available, the WHO estimates that 5 percent of TB cases have multi drug-resistant disease. This translates into 480,000 cases, and 190,000 deaths each year.

Conventional treatment regimens for MDR-TB can take up to two years and have low cure rates - with 50 percent of patients failing to get better. Experts say this is largely because patients find it very hard to stick with the required months and months of taking powerful medicines, which can have some unpleasant side-effects, so often give up their treatment.

Raviglione said the shorter regimen is designed for patients with so-called "uncomplicated" MDR-TB -- in other words people whose MDR-TB is not resistant to the most important second-line drugs, fluoroquinolones and injectables.

FASTER TEST, SPEEDIER TREATMENT

The most reliable way to rule out resistance to second-line drugs is a newly recommended diagnostic test - called MTBDRsl – that can identify genetic mutations in MDR-TB strains.

This test, which the WHO said should be used as part of its new guidelines, can give a result within 48 hours, far more quickly than the 3 months or longer currently needed to find out which drugs a patient's TB is resistant to.

"We hope that the faster diagnosis and shorter treatment will accelerate the much-needed global MDR-TB response," said Karin Weyer, a WHO TB testing and diagnostics expert.

TB is one of the world biggest infectious disease killers and claimed 1.5 million lives in 2014 - more than HIV/AIDS and almost three times as many as malaria. Some 95 percent of TB deaths are in poorer countries.

Superbug, or drug-resistant, forms of the disease have spread worldwide, fueled by patients getting inadequate treatment. Like regular TB, superbug strains can spread from person to person through the air.

(Reporting by Kate Kelland; Editing by Mark Heinrich)