Resistance to Backup Tuberculosis Drugs Increases

In countries such as South Africa, drugs commonly used to treat tuberculosis are becoming less effective as strains of the diseases develop resistance. Image: Tom Fox/Dallas Morning News/Corbis

Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...

Read More

From Nature magazine

More than 40% of tuberculosis infections that are resistant to front-line treatments are also resistant to some common backup drugs, according to research published this week in The Lancet1.

Efforts to control tuberculosis are being hampered by the emergence of multidrug-resistant (MDR) strains of the disease, which resist treatment with two front-line antibiotics, rifampicin and isoniazid. In some parts of the world, as many as 50% of tuberculosis cases are resistant to these drugs2. Alternative treatment options are toxic and expensive, relying on second-line drugs that are not as effective and must be given in lengthy courses. Unfortunately, the majority of MDRtuberculosis cases occur in developing countries that cant afford the several billion dollars that the global Stop TB Partnershipestimates3 will be required to combat the disease.

More recently, strains of tuberculosis have emerged that are resistant not only to front-line antibiotics, but also to one or more drugs within each of the two most important classes of second-line drugs broad-spectrum antibiotics called fluoroquinolones, and injectable agents (amikacin, capreomycin and kanamycin). This extensively drug-resistant (XDR) tuberculosis heralds a disturbing trend towards infections that are virtually untreatable.

It is critical that we take steps now in diagnosing, treating and preventing MDR tuberculosis so that it doesnt turn into XDR tuberculosis, says Peter Cegielski, medical officerfor the division of tuberculosis elimination at the US Centers for Disease Control and Prevention in Atlanta, Georgia, and a co-author of the Lancet study1.

Under the radar Cegielski and his colleagues investigated the prevalence of resistance to second-line drugs among 1,278 people diagnosed with MDR tuberculosis in eight countries most of which are on the list of nations with a high MDR-tuberculosis burden. They found that 43.7% of the study participants were infected with a tuberculosis strain that was resistant to at least one second-line drug, and 6.7% of the infections proved to be XDR tuberculosis.

The team also identified factors associated with a risk of developing resistance to second-line drugs, and found that the most significant was previous treatment with the same drugs. By identifying the risk factors, we can help shape practice to ensure that patients are diagnosed and treated properly, says Cegielski.

Originally posted here:
Resistance to Backup Tuberculosis Drugs Increases