Extensively Drug-resistant Tuberculosis (XDR-TB): The Value Of A Clear Definition

Main Category: Tuberculosis
Also Included In: Infectious Diseases / Bacteria / Viruses
Article Date: 28 Sep 2007 - 18:00 PDT

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Extensively drug resistant tuberculosis (XDR-TB) represents a spectre for the civil society and a major challenge for the TB control community.

The ERS has played a key role in fighting XDR-TB, promoting important studies and publishing some of them in the European Respiratory Journal, the scientific publication of the ERS. In addition, some relevant studies on XDR-TB have been developed by TBNET (TuBerculosis Network in Europe Trials group), a network of research centres operating within the ERS study group "Tuberculosis".

In this issue, the TBNET study reports on 4,583 confirmed TB cases in Italy, Germany, Estonia and Russia (Archangels Oblast).

Treatment outcomes of 64 XDR (1) cases, 267 multidrug-resistant (MDR) (2) cases resistant to all first-line drugs, and of 94 "other" MDR cases (susceptible, at least, to one first-line anti-TB drug) are compared.

The results of the study demonstrate that XDR cases have a worse outcome (death or failure, i.e. treatment fails to render the patient non-infectious) than MDR cases resistant to all first-line drugs, and of "other" MDR cases (susceptible, at least, to one first-line anti-TB drug).
The study also demonstrates that the XDR definition proposed by WHO has both a clinical (predicts poor outcome), and operational value (confirming these cases are resistant to both first-line drugs and key second-line ones).

(1) XDR: cases resistant at least to isoniazid and rifampicin, plus at least one fluoroquinolone (new generation second-line drug) and one injectable second-line drug
(2) MDR: cases resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 8,000 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).

European Respiratory Society