A Better Tool to Diagnose Tuberculosis

Up to 30 percent of the world’s population is infected with Tuberculosis (TB), but in many areas of the world, TB diagnosis still relies on insensitive, poorly standardized, and time-consuming methods. A new diagnostic tool, endorsed by the World Health Organization (WHO), may change that. Dr. Thomas Bodmer from the University of Bern, Switzerland, shows how it’s done in the April issue of JoVE.

Currently, TB is diagnosed through either a skin test, which produces a small bump on the patient’s arm when administered and needs to be checked after 72 hours, and through smear microscopy, a method that was developed over a century ago. The new test is fully automated and takes about an hour and a half to give results. It is also able to determine if the patient is infected with a multidrug-resistant strain of the bacteria.

“The Xpert MTB/RIF assay is intended for use with specimens from patients for whom there is suspicion of pulmonary tuberculosis and who fulfill the criteria outlined in the accompanied text,” said Dr. Bodmer, who co-authored the article.

WHO endorsed the test in 2010, and is working to roll it out across tuberculosis-affected countries. An important aspect of this is training people to use the device, and the JoVE video-article will help with standardization.

“TB is one of the most deadly infectious diseases worldwide and accurate and rapid diagnosis is essential for timely and proper treatment. This test is expected to dramatically improve the diagnosis of TB,” said JoVE Science Editor, Dr. Charlotte Frank Sage. “Publication of the protocol in JoVE allows researchers around the world to see a detailed demonstration of this diagnostic tool and will aid in establishing this technology in their laboratories and clinics.”

To see the full video-article, please click here.

Are Biofilms to Blame for TB Drug Resistance?

According to the World Health Organization (WHO), one-third of the world’s population is currently infected with tuberculosis bacteria. Despite its prevalence, very little is known about why the bacteria is so resistant to treatment. But, researchers at the University of Pittsburgh have been developing a new way of culturing tuberculosis bacteria, which could lead to new insights and treatments.

“This is a significant step forward in TB research,” said paper-author Dr. Anil Ojha, “because it shows in a very reproducible way how to culture biofilms.”

Though Mycobacterium tuberculosis has been cultured before, it is difficult to culture the bacteria in the biofilms— organized, multicellular structures— that give the bacteria its extraordinary resilience against environmental stresses and antibiotics. A tuberculosis biofilm can tolerate more than 50 times the minimal therapeutic dose of anti-tuberculosis drugs.

M. tuberculosis is difficult to treat,” said Ojha. “It takes six to nine months of chemotherapy and after two months, most patients convert to culture-negative and smear-negative, though there is still bacteria there, and if you end treatment, the patient will have a relapse.”

It is not known whether or not tuberculosis forms biofilms in the host, and whether that is the reason the microbes are so resistant to treatment, but according to Dr. Ojha, certain niches in the body have similar conditions to those that are required to culture biofilms in the lab.

The next step for the lab is to determine whether tuberculosis forms biofilms in its hosts, and to understand the genetic factors involved in biofilm formation. If tuberculosis does form biofilms in patients, understanding the genetics of biofilm formation could ultimately lead to more effective treatments for tuberculosis.

The article was published in JoVE last week and can be viewed here.