New antibiotics are becoming available for the first time but without accurate diagnostics, clear treatment guidelines, and improved control efforts, their effectiveness could be rapidly lost.
A report finds that the rise of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) threatens to derail decades of progress in controlling the disease.
Although a small number of repurposed and new drugs have recently become available to treat drug-resistant TB (including bedaquiline, delamanid, and linezolid), the authors in The Lancet Respiratory Medicine warn that the effectiveness of the drugs could be rapidly lost.
Accurate diagnostic tests are needed to deliver individually targeted treatments, along with clear prescription guidelines on appropriate use and improved control efforts to prevent transmission, optimal dosing and administration.
TB kills more people each year than any other infectious disease, including HIV/AIDS. In 2015, TB was estimated to have killed 1.8 million people. Six countries account for 60% of the total number of cases of TB worldwide – India, Indonesia, China, Nigeria, Pakistan and South Africa.
Approximately 1 in 5 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 (resistant to two essential first-line TB drugs, isoniazid and rifampicin) or XDR (also resistant to fluoroquinolones and second-line injectable drugs).
Globally in 2015, there were an estimated 480,000 cases of MDR-TB, with approximately half of these cases being in India, China, and Russia. But, migration and travel mean that highly drug-resistant TB strains have emerged in almost every part of the world.
MDR and XDR-TB are associated with high mortality, are a threat to health-care workers, prohibitively expensive to treat, and are therefore a serious public health problem.
Until recently, it was thought that drug-resistant strains of TB were less transmissible, and that MDR- and XDR-TB was mainly acquired by individuals as a result of poor compliance to treatment.
However, recent molecular and epidemiological studies, outlined in the Commission, have challenged this belief.
“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,” says lead author of the Commission Professor Keertan Dheda, University of Cape Town.