Multidrug-resistant tuberculosis in Europe: Managed or mismanaged?

Every year, over 9 million new cases of TB are reported worldwide, with almost 2 million deaths. To make matters worse, the threat of multidrug-resistant bacilli has emerged, making the disease more expensive and difficult to treat.
In 2010, the World Health Organization (WHO) reported an unexpectedly high prevalence of multidrug-resistant tuberculosis with peaks of 25% or more among new cases of TB in some settings. At present, an estimated 5% of the more than 9 million people who develop TB around the world every year are infected with an MDR-TB strain, i.e. a strain that is resistant to (at least) the two most powerful anti-TB drugs currently available, isoniazid and rifampicin.
During a joint press conference at the 20th Annual Congress of the European Respiratory Society, experts in the field of tuberculosis will address current challenges in the management of the disease, such as TB/HIV co-infection and the rise of resistant TB strains as well as present an European TB research network, TBNET, aimed at advancing science, clinical research, training, policy development and public health.
“TB is a global problem that needs to be dealt with by the international community,” urges Professor Giovanni Battista Migliori, ERS Assembly Head of Respiratory Infections and Director of the WHO Collaborating Centre for TB and Lung Disease, Tradate, Italy.
TBNET is an ERS-supported Clinical Research Collaboration (CRC) in the area of tuberculosis research, working in close collaboration with WHO and ECDC. The main areas of focus are the development of improved diagnostic methods and new drugs as well as the prevention and control of drug-resistant TB.
“One of the biggest problems in most European countries is that treatment success rates are far below the 85% target set by the WHO World Health Assembly, thereby promoting resistance to common anti-tuberculosis drugs” explains Dr Davide Manissero, Head of Section Respiratory Tract Infections and Tuberculosis Programme Coordinator at the ECDC, Stockholm, Sweden.
“Part of the problem is that treatment for multidrug-resistant TB takes substantially longer than for uncomplicated TB; treatment of MDR requires up to 24 months` worth of treatment. The drugs needed are less effective than the first-line drugs for the treatment of drug-susceptible TB and cause more side effects,” says Dr Manissero.
For multidrug-resistant TB, the treatment success rate is extremely low (31%).
A further threat is extensively multidrug-resistant TB (XDR-TB), defined as MDR-TB that is additionally resistant to any of the fluoroquinolones and any of the three injectable second-line anti-TB drugs, amikacin, kanamycin, and capreomycin.
The M/XDR-TB threat is further aggravated by the poor outcomes of this group of patients. In a cohort of 1,100 patients only 30.9% of those who started treatment in 2006 (2006 cohort) were successfully treated in the EU/EEA. A high percentage (13.2%) of these MDR-TB cases defaulted from treatment, increasing the risk for XDR-TB.
The latest figures on multidrug-resistant tuberculosis show about 440,000 cases of MDR-TB, causing at least 150,000 deaths. XDR-TB has been reported officially from 58 countries as of March 2010, explains Professor Mario Raviglione, Director, Stop TB Department, WHO, Geneva. “Of all cases of TB, over a million occurred among people living with HIV/AIDS and nearly half a million were fatal.”
It is unclear whether HIV infection is a risk factor for drug-resistant or MDR-TB. Known factors that can promote the development of resistance include malabsorption, drug intolerance, drug interactions, and noncompliance among intravenous drug abusers.
Dr Raviglione concludes: “Proper TB control based on early and rapid detection and adequate treatment until cure must be in place everywhere to interrupt transmission, avert deaths, and prevent MDR-TB.”
(idw, 09/2010)

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