More than 60 per cent of patients diagnosed with a type of tuberculosis that is very difficult to treat were cured with aggressive drug treatment, a study from Peru suggests.

Extensively drug-resistant TB or XDR-TB is a form of tuberculosis that is resistant to all of the most effective drugs.

'It's essential that the world know that XDR-TB is not a death sentence.'—Study author Carole Mitnick

In Thursday's issue of the New England Journal of Medicine, researchers reported the treatment success among 650 TB patients in Lima who were studied between 1999 and 2002. Of these cases, 48 had XDR-TB, and none was also infected with HIV.

The study reported that treatment of the 48 patients with a structured, comprehensive, community-based approach and aggressive antituberculosis medications — an average of five or six medications per patient — achieved a cure in 29 patients.

"It's essential that the world know that XDR-TB is not a death sentence," said lead author Carole Mitnick, an instructor in the Department of Global Health and Social Medicine at Harvard Medical School in Boston.

"As or even more importantly, our study shows that effective treatment does not require hospitalization or indefinite confinement of patients," she added in a statement.

By the end of treatment, 60.4 per cent in the XDR-TB group were cured compared to 66.3 per cent with multi-drug resistant tuberculosis that resists the two first-line drugs for TB.

The XDR-TB patients had frequent contact with health-care workers. Daily, supervised treatment ensured a high level of adherence while allowing potential issues or side-effects to be addressed quickly, the study's authors said.

Those factors may explain why the Peruvian doctors were able to achieve a success rate that exceeded that of hospitals in Europe and the U.S., said the team, which was funded by the Bill and Melinda Gates Foundation.

It's possible the strains causing disease in Peru were also less resistant to drugs, Dr. Mario Raviglione of the World Health Organization said in a journal commentary on the findings.

"This encouraging result constitutes a true change in the current perception of the disease as a virtual death sentence," Raviglione wrote. "The challenge is to make this approach a sustainable reality worldwide."

Doing so will require clear planning, financial commitment and adequate resources, technical capacity and partnership, he said.

Technically, MDR-TB is now defined as resistance to at least two first-line drugs, isoniazid and rifampin. XDR-TB is resistant to rifampin, isoniazid, a fluoroquinolone and a second-line injectable drug.

A second study appearing in the same issue found XDR-TB patients in the U.S. were about eight times as likely as MDR-TB patients to die from tuberculosis or surgery to treat it.

Of 174 patients treated at National Jewish Health in Denver, 10 had XDR-TB, study author Dr. Michael Iseman and his colleagues said.

The XDR-TB patients were 2.5 times as likely to die from all causes during followup, with 14 deaths among the 164 MDR-TB patients compared to half the XDR patients.