ArticlesTreatment of extensively drug-resistant tuberculosis in Tomsk, Russia: a retrospective cohort study
Introduction
Every year an estimated 490 000 new cases of multidrug resistant (MDR) tuberculosis arise worldwide, with a prevalence that is thought to be three times greater than this number.1, 2 MDR tuberculosis—caused by strains of Mycobacterium tuberculosis that are resistant to isoniazid and rifampin, the backbone of first-line treatment against tuberculosis—is more difficult and costly to treat than non-drug-resistant tuberculosis.3, 4 However, extensively drug-resistant (XDR) tuberculosis is an even greater threat to control of the disease. XDR tuberculosis is a subgroup of MDR tuberculosis, which is also resistant to the most effective second-line drugs against tuberculosis: any second-line aminoglycoside or capreomycin, and any fluoroquinolone.5, 6 Although the worldwide burden of XDR tuberculosis is unknown, 7% of isolates of MDR tuberculosis referred to supranational reference laboratories from 2000 to 2004 were XDR cases.1
Scarce therapeutic options and high mortality rates associated with XDR tuberculosis are a concern. A report of an outbreak of XDR tuberculosis in 53 HIV-positive patients in the province of KwaZulu Natal in the Republic of South Africa, during which 52 patients died after about 16 days from diagnosis of tuberculosis, has been a warning for the global tuberculosis community of the dangers of allowing drug resistance to flourish unchecked.7 Other reports from non-HIV-infected patients have reinforced the alarm.8, 9, 10, 11, 12, 13
Although XDR tuberculosis is referred to by some as being untreatable, aggressive clinical and programmatic management can greatly improve the outcome of the disease, which provides hope to the many infected patients. The aim of this study is to describe the clinical characteristics, management, and outcomes of patients treated for MDR and XDR tuberculosis in Tomsk, Russia.
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Study setting
Tomsk Oblast is located in western Siberia, Russia, and has about 1·1 million inhabitants, roughly half of whom live in remote rural villages. Between 1998 and 2002, rates of MDR tuberculosis in Tomsk rose from 6·5% to 13·7% for newly detected cases, and from 26·7% to 43·6% for previously treated cases. During this time, Tomsk had implemented DOTS (directly observed treatment, short-course), the treatment strategy of WHO for non-drug-resistant tuberculosis, consisting of short-course
Results
Of the 636 patients who had treatment against MDR tuberculosis in the study period, 608 had documented baseline MDR tuberculosis and 28 were treated for presumed MDR tuberculosis on the basis of treatment or contact history, or MDR tuberculosis diagnosed before moving to Tomsk. These 28 patients are excluded from the analysis. 29 patients (4·8%) met the definition of XDR tuberculosis before starting treatment for MDR tuberculosis. The proportion of patients with XDR tuberculosis did not vary by
Discussion
We have shown that, although treatment outcomes were worse in patients with XDR tuberculosis than those in patients with MDR tuberculosis who were infected with strains that were susceptible to fluoroquinolones and at least one of the parenteral drugs, 48% of patients with XDR tuberculosis—often termed untreatable in press reports—responded favourably to treatment. Although our results for treatment outcomes were similar to those reported elsewhere,13, 26 one major difference was that the
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