Issue: October 2012
October 01, 2012
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CDC researchers find high rates of MDR and 
XDR TB in eight countries

Issue: October 2012
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Researchers from the CDC have found higher overall levels of extensively drug-resistant tuberculosis in eight countries, as well as a high prevalence of resistance to at least one second-line drug among those with multidrug-resistant tuberculosis.

Perspective from Joel Ernst, MD

“Drug-resistant TB is more difficult and costly to treat and more often fatal,” Tracy Dalton, PhD, of the CDC, said in a press release. “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. So far, extensively drug-resistant TB has been reported in 77 countries worldwide, but exact prevalence remains unclear.”

The researchers conducted a prospective cohort study from 2005 to 2008. Patients with confirmed pulmonary MDR TB who were starting second-line treatment were enrolled. The patients were from one of eight countries: Estonia, Latvia, Peru, Philippines, Russia, South Africa, South Korea and Thailand.

Among the 1,278 patients enrolled, 43.7% had resistance to at least one second-line drug, ranging from 33.3% in Thailand to 62% in Latvia. Fluoroquinolone resistance was seen in 12.9% of the patients and 20% of patients were resistant to at least one second-line injectable drug. The prevalence of resistance to other oral second-line drugs was 27.1%. XDR TB was seen in 6.7% of patients.

The strongest risk factor for resistance was previous treatment for MDR TB with any second-line drug. Patients in the hospital at time of enrollment were at risk for resistance to fluoroquinolones and second-line injectable drugs, as well as for XDR TB. Fluoroquinolone resistance and XDR TB were more common in women. Patients with HIV infection had less fluoroquinolone resistance. Unemployment, a history of imprisonment, alcohol abuse and tobacco use were also risk factors for resistance to second-line injectable drugs.

“Social factors should be taken into account in the management of TB,” Dalton said in the press release. “Our country-specific results can be extrapolated to guide in-country policy for laboratory capacity and for designing effective treatment recommendations for MDR TB.”

For more information:
  • Dalton T. Lancet. 2012;doi:10.1016/S0140-6736(12)60734-X.

Disclosure: The researchers report no relevant financial disclosures.