Quick TB Test Builds Up Arsenal Against Drug-Resistant Bacteria | WAMU 88.5 - American University Radio

NPR : News

Filed Under:

Quick TB Test Builds Up Arsenal Against Drug-Resistant Bacteria

The people on the front lines of tuberculosis control have their hands full, but their biggest challenge for the moment may be containing strains of the disease that are resistant to drugs.

Worldwide the number of TB cases is going down. The bad news is that the number of drug-resistant cases is going up. The World Health Organization estimates that the number of reported TB cases that were multi, extremely- or totally-drug resistant doubled between 2009 and 2011.

Until recently, it was extremely difficult to even diagnose drug-resistant TB, particularly in developing countries where the disease is most prevalent. Tests had to be sent to fancy labs and could take up to three months to process.

But hope arrived a few years ago, in the form of a new screening tool called Xpert. It was designed to identify TB bacteria and the most common form of drug resistance in only two hours. But as a new technology, no one was quite sure how effective it was.

Now, a comprehensive analysis of Xpert's performance, published Thursday in the influential Cochrane Library, validates the test as an accurate tool for detecting resistance to one of the leading TB drugs, rifampicin.

At $17,000 for the machine and $9.98 for each test, Xpert is pricey. But this stamp of approval could encourage more health departments in TB endemic countries to spend the dough on this new method of testing.

In the study, researchers at the University of Washington and McGill University analyzed 18 previously published studies involving almost 8,000 TB patients.

They found that, compared to the conventional methods, Xpert could accurately detect a TB infection 88 percent of the time and rifampicin resistance 94 percent of time.

Health workers in the field are a fan of it, too. Doctors in Cape Town, South Africa working with Doctors Without Borders tell Shots the Xpert is a "game changer" in TB control.

They say that by identifying drug-resistant TB earlier, these highly dangerous strains of the air-borne bacteria can be contained and kept from spreading.

The Xpert machine examines the nucleic acid in a patient's sputum – the mucus coughed up from the upper respiratory tract. The spit is put in a cartridge, which is then stuck into the Xpert machine. Within two hours, a doctor will know if the patient has TB and if that form of TB is resistant to rifampicin.

In the conventional TB test, still widely used today, a medical worker looks for the bacteria under the microscope.

If there are signs of an infection, the sample is then sent out for confirmation by culturing the bacteria in a laboratory. This can take up to six weeks to get results, and testing for drug-resistant strains of the bacteria takes even longer.

TB is the second leading cause of death from an infectious disease after HIV, killing an estimated 1.4 million people around the globe in 2011.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

NPR

'Madame Secretary' Pales In Comparison To 'The Good Wife'

The CBS dramas about women juggling family lives and high-intensity jobs showcase excellent acting. But while The Good Wife is one of the best shows on TV, Madam Secretary's writing is disappointing.
NPR

Sweet: Dunkin' Donuts and Krispy Kreme Pump Up Pledge On Palm Oil

Two major doughnut chains have bowed to consumer pressure to better police their palm oil purchases. Environmentalists say its a win for consumers, trees and animals.
NPR

Billionaire GOP Donor Finally Opens Checkbook For 2014

Sheldon Adelson, the Las Vegas casino magnate, is giving $20 million to GOP-oriented "social welfare" groups for use in midterm campaigns.
NPR

Apple: iOS 8 Prevents Cooperation With Police Unlocking Requests

In the rollout of its new mobile operating system, Apple says it has made it technically impossible for the company to unlock phone data, even in response to a law enforcement warrant.

Leave a Comment

Help keep the conversation civil. Please refer to our Terms of Use and Code of Conduct before posting your comments.