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Experts warn new TB drugs’ effectiveness could be lost

Global rise of drug-resistant TB is at a crossroads, says report

Adrian O'Dowd

Friday, 24 March 2017

Experts are warning today that the effectiveness of new drugs in treating tuberculosis (TB) could be lost without real efforts to support their introduction.

A report* published today in The Lancet Respiratory Medicine journal to coincide with World TB day today, says that the rise of multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB threatens to derail decades of progress in controlling the disease.

The report was written by an international team of experts from The Lancet Respiratory Medicine Commission.

TB is responsible for killing more people each year than any other infectious disease. In 2015, TB was estimated to have killed 1.8 million people.

Approximately one in five cases of TB are now resistant to at least one major anti-TB drug and approximately 5% of all cases of TB are classed as MDR or XDR, both of which are associated with high mortality.

The treatment of TB was revolutionised in the 1950s with the introduction of three antibiotics – streptomycin, isoniazid, and para-aminosalicylic acid – but the extensive overuse and “abuse” of antibiotics worldwide has led to a rise in bacteria that are drug resistant.

The new report says that a small number of repurposed and new drugs have recently become available to treat drug-resistant TB (including bedaquiline, delamanid, and linezolid), but their effectiveness could be lost without:

  • accurate diagnostic tests to deliver individually targeted treatments
  • clear prescription guidelines on appropriate use
  •  improved control efforts to prevent transmission
  • optimal dosing and administration
  • well-functioning health care systems

Lead author of the Commission, Professor Keertan Dheda from the University of Cape Town in South Africa, said: “Resistance to anti-tuberculosis drugs is a global problem that threatens to derail efforts to eradicate the disease. Even when the drugs work, TB is difficult to cure and requires months of treatment with a cocktail of drugs.

“When resistance occurs, the treatment can take years and the drugs used have unpleasant and sometimes serious side effects. Cure rates for drug resistant TB are poor and people can remain infectious and at risk of spreading the disease.

“Improved diagnostic tests are on the horizon, but we need huge efforts to increase their accuracy, use them for active case finding in the community, and eventually make them available in low income countries so as to inform treatment decisions and preserve the efficacy of any new antibiotic drugs for TB.”

Writing in a linked comment,** Dr David Dowdy from the Johns Hopkins Bloomberg School of Public Health in the USA, said: “Ultimately, Dheda and colleagues are describing an epidemic that is at a crossroads. Every year, strains of drug-resistant tuberculosis will emerge that are more transmissible, more difficult to treat, and more widespread in the community.

“Yet we also have more tools at our disposal than ever before. And unlike for most other drug-resistant pathogens, we have evidence that, with a comprehensive response, drug-resistant tuberculosis epidemics can be rapidly reversed.

“Over the next decade, it is quite possible that we will see a drug-resistant tuberculosis epidemic of unprecedented global scale. But it is also possible that the next decade could witness an unprecedented reversal of the global drug-resistant tuberculosis burden.”

* Dheda K, Gumbo T, Maarten G, et al. The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis. The Lancet Respiratory Medicine, March 2017. DOI: 10.1016/S2213-2600(17)30079-6

** Grainger E, Hellier R, Stanley D. The war on tuberculosis must continue. The Lancet Respiratory Medicine, March 2017. DOI: 10.1016/S2213-2600(17)30082-6

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