Comprehensive Treatment of Extensively Drug-Resistant Tuberculosis

24 Oct 2008

Paul Chinnock

Source: New England Journal of Medicine (see original article)

Comments

Since it was first described in 2006 extensively drug-resistant tuberculosis (XDR-TB)* has been reported in 45 countries. Some of these countries are in the developing world and already have a high TB burden. The situation is of great concern; can patients with XDR-TB be cured in low-resource settings, where there is inadequate infrastructure and insufficient numbers of trained staff?

Outpatient treatment of TB is commonplace and it has been shown to be appropriate and effective in low-resource settings, but can it be used successfully with XDR-TB pateints? A retrospective study in Peru reports encouraging results.

The investigators worked with 810 TB patients who had been treated unsuccessfully for the disease or had had contact with patients with multidrug-resistant tuberculosis (MDR-TB) *. They were referred for free individualized therapy, including drug treatment, resective surgery, adverse-event management, and nutritional and psychosocial support. The researchers tested isolates from 651 of these patients for XDR-TB and they developed regimens that included five or more drugs to which the infecting isolate was not resistant.

Only 48 of those tested had XDR-TB; the remaining 603 patients had MDR-TB. Twenty-nine of the XDR-TB patients (60.4%) completed treatment or were cured, as compared with 400 patients (66.3%) with MDR-TB. The authors point out that their cure rates are higher than those achieved in most comparable studies in developed countries.

While the study only involved a small number of XDR-TB cases and, as the authors discuss, had other limitations, it has provided some evidence that aggressive regimens, as part of a comprehensive outpatient therapeutic approach, can be successful in treating this disease in a developing nation.

The Peruvian study, however, involved patients who were not infected with HIV. As the authors point out, there is evidence from South Africa that XDR-TB can be rapidly fatal in HIV-positive patients. Treating such patients is likely to prove to be a greater challenge.

* MDR-TB refers to strains of Mycobacterium tuberculosis that are resistant to at least both isoniazid and rifampicin (two first-line anti-TB drugs). XDR-TB refers to strains that are additionally resistant to at least two of the six classes of second-line drugs.

Reference

1. Gandhi NR, Moll A, Sturm AW, et al (2006). Extensively drug-resistant tuberculosis as a cause of death in patients co-infected with tuberculosis and HIV in a rural area of South Africa. Lancet; 368:1575-1580. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17084757