(August 25, 2008 - Insidermedicine) Extensively drug-resistant tuberculosis can respond to treatment nearly half the time if an aggressive approach is used, according to research published in The Lancet.

Here is some information on the management of patients treated for TB who relapse:

•    Most relapses occur within the first 6 to 12 months after completion of therapy.

•    In patients who received self-administered therapy or a non-rifamycin regimen and who have a relapse, the risk of acquired drug resistance is substantial.

•    If initial drug susceptibility testing was not performed and the patient relapses with a rifamycin-containing regimen, there is a high likelihood that the organisms were resistant from the outset.

Researchers from Harvard Medical School performed drug susceptibility testing on 608 individuals with multidrug-resistant TB. Patients were then treated with the goal of providing at least five drugs to which their TB was susceptible. If five such drugs were not available, the researchers used drugs the patients had not used in the past.

Overall, 4.8% of patients had extensively drug-resistant TB. This condition was indeed harder to treat, with treatment failure occurring in 31% of these patients, compared with only 9% of those without extensively drug-resistant TB. Still, fully 48% experienced treatment cure or completion.

Today's research demonstrates that extensively drug-resistant TB, widely regarded as impossible to treat, may respond to a very aggressive treatment approach.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.