Drug resistant TB levels described as alarming by new international study

A large, international study published in The Lancet reveals alarming levels of tuberculosis (TB) that are resistant to both first-line and second-line drugs.

The findings show high prevalence of resistance to at least one second-line drug (43.7%) among multidrug-resistant (MDR) TB patients from eight countries in Africa, Asia, Europe, and Latin America. Worse still, the study found higher than expected overall levels of extensively drug-resistant (XDR) TB.

Extensively drug-resistant tuberculosis (XDR-TB) is a form of tuberculosis caused by bacteria that are resistant to some of the most effective anti-TB drugs.

In the Preserving Effective TB Treatment Study (PETTS), Tracy Dalton, the study’s lead author from the US Centers for Disease Control and Prevention (CDC), says that XDR-TB has been reported in 77 countries worldwide, but the exact prevalence remains unclear.

“Drug-resistant TB is more difficult and costly to treat, and more often fatal," Tracy Dalton explained. 

"Internationally, it is particularly worrisome in areas with fewer resources and less access to effective therapies.  As more individuals are diagnosed with, and treated for, drug-resistant TB, more resistance to second-line drugs is expected to emerge,” Tracy added. 

According to the study, XDR TB was detected in 6.7% patients overall, with prevalence in South Korea (15.2%) and Russia (11.3%) more than twice World Health Organisation's global estimates for the same time period (5.4%).

"There needs to be more investment in research and development for new vaccines, diagnostics and treatments for TB (and MDR-TB)," said RESULTS National Advocacy Director Kate Finch.

"After all, MDR-TB was originally caused by inappropriate or incomplete TB  diagnosis & treatment," Ms Finch added.

Among the study’s other key findings were that risk of XDR disease was more than quadrupled in previously treated patients, and previous treatment with second-line drugs was consistently the strongest risk factor for resistance to these drugs.

Further analysis also found unemployment, a history of imprisonment, alcohol abuse, and smoking as factors associated with resistance to second-line injectable drugs.

"The more cases of MDR-TB that are diagnosed and treated, the more resistance will occur to second-line drugs. This then leads to higher cases of XDR-TB, which is practically impossible to treat," continued Ms Finch.

Recently RESULTS has submitted advice on AusAID's new Medical Research Strategy, which is aimed to help poor countries increase access to health technologies that work, and emphasised the rates of MDR-TB in the Asian region.

"One of the first priorities for the strategy is investing in public-private partnerships for TB R&D," continued Ms Finch.

"This investment will need to be long term and sustained if new products are really to make it through the whole development cycle and to those most at risk.

"It is really encouraging to see AusAID invest in R&D with a focus on poverty-related disease at a time when other governments are pulling back," said Ms Finch.