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WASHINGTON (Reuters) - Two existing drugs used in combination appear to offer great promise against the most dangerous form of tuberculosis, U.S. researchers said on Thursday.
AstraZeneca's MERREM I.V., also called meropenem, used together with clavulanate, sold by GlaxoSmithKline in combination with amoxicillin as the drug Augmentin, killed laboratory-grown strains of TB, they said.
In addition, the combination worked in lab dishes against 13 extensively drug-resistant, or XDR, TB strains taken from patients with this hardest-to-treat form of TB, the researchers wrote in the journal Science.
Increasing numbers of cases of the infectious bacteria that defy standard tuberculosis drugs are appearing worldwide.
The researchers said they plan to launch a clinical trial using the drugs on about 100 XDR-TB patients in South Korea this year. Another clinical trial is planned in South Africa.
People with XDR-TB have few treatment options, and death rates are high.
"There are increasing numbers of cases of TB that are drug resistant, either multi-drug resistant (MDR) or extensively drug resistant (XDR), which are extremely difficult and costly to treat, if possible at all," John Blanchard of Albert Einstein College of Medicine of Yeshiva University in New York, one of the researchers, said in a telephone interview.
"There have been no drugs introduced in the chemotherapy of TB in 40 years. So this would be the first new class of compounds that could potentially be approved for the treatment of TB in the last 40 years. So that's exciting," he added.
MERREM I.V. is an intravenous antibiotic used against a variety of bacterial infections. Augmentin also is an antibiotic, although clavulanate by itself is not.
The researchers said clavulanate inhibits a bacterial enzyme that typically protects TB bacteria from meropenem.
The researchers noted that the drugs are considered very safe and are approved by the U.S. Food and Drug Administration for adult and child use.
Cases of drug-resistant tuberculosis are being seen around the world at the highest rates ever, according to the U.N. World Health Organization. Of 9 million new TB cases annually, the WHO said about 490,000 are MDR-TB and about 40,000 are XDR-TB, based on 2006 data.
"We see tremendous potential for treating not only XDR-TB cases, but also routine TB cases," Dr. Brian Currie of Albert Einstein College of Medicine, another of the researchers, said in a statement.
Albert Einstein College of Medicine said it has filed a patent application for this TB treatment.
Editing by Maggie Fox and David Wiessler