How can we combat drug-resistant TB?
Coinciding with World TB Day, new consensus statements have been drafted to address the growing problem of multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis.
These statements - published in the European Respiratory Journal - are significant, because this is the first time that doctors treating patients with these new strains of tuberculosis (TB) have reached a consensus on patient management.
The major obstacle to developing guidelines for treatment of these forms of TB has been a lack of clinical evidence. These forms of the disease are so recent, it could be many years before sufficient evidence is available to form the basis of successful treatment.
Although in many parts of the world - the Americas, Europe, western Pacific and southeast Asia - incidence of TB is decreasing, multi-drug resistant TB (MDR-TB) - where the disease is resistant to at least isoniazid and rifampicin - is on the rise.
The first cases of MDR-TB were reported in "resource poor, high burden" areas in the 1980s. The World Health Organization (WHO) now estimate that about 450,000 new cases of MDR-TB occur each year, mostly within Europe.
Lead author Prof. Christoph Lange, head of the Respiratory Infections Assembly at the European Respiratory Society, says:
"These consensus statements provide very valuable support for physicians treating patients with these deadly conditions in all parts of Europe. The current management of patients with multidrug- and extensively drug-resistant TB is complex, very costly for health care systems and burdensome for those who are affected."
"We have harmonised individual expert opinions on the management of multidrug- and extensively drug-resistant TB in adults and children to ensure that consensus is available where clinical evidence is still lacking. As clinicians we hope to improve the treatment of multidrug- and extensively drug-resistant TB and the life of our patients who suffer from these difficult-to-treat conditions."
Most TB patients also have other potentially fatal diseases that affect their immune systems.
Meanwhile, a commentary on "totally-drug-resistant tuberculosis" in The Lancet Respiratory Medicine - a term that WHO has not yet approved - reminds that another problem in combatting drug-resistant TB is that most TB patients also have other potentially fatal diseases that affect their immune systems.
In addition, many TB patients are under-nourished, which can have a substantial impact on the immune system and may affect how the patient responds to vaccination.
Resistance to all available TB drugs was first observed in Italy in 2003. Doctors treating these patients found that the disease was resistant to all first- and second-line drugs, including treatments such as rifabutin, clofazimine, dapsone, clarithromycin and thiacetazone.
The authors, from the Karolinska Institutet in Stockholm, Sweden, suggest that - in the wait for new and effective vaccines - existing drugs may be repurposed as potentially effective treatments.
The authors recommend investigation of peptide-conjugated phosphorodiamidate morpholino oligomers for this, as well as older drugs such as ibuprofen or verapamil.
"However," writes Prof. Keertan Dheda and colleagues of the University of Cape Town, South Africa, in the conclusion to their study on "untreatable" TB, which is also published in The Lancet Respiratory Medicine, "specific efforts for tuberculosis control will not succeed if broader issues - reduction of poverty, over-crowding, political stability, and rates of HIV - are not addressed."
"There is also an urgent and comprehensive need to scale up protective measures and strategies against tuberculosis in health care workers. The large-scale emergence of functionally untreatable tuberculosis needs governments and international agencies to take serious steps to reform the global economy to reduce poverty, make existing drugs available in resource-poor development."
Medical News Today recently reported on a briefing paper from Doctors Without Borders, which referred to drug-resistant TB as the "biggest threat to global health you've never heard of."
Written by David McNamee
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