Study May Alter Current Views on Drug-Resistant TB

THURSDAY, March 8 (HealthDay News) -- Most cases of drug-resistant tuberculosis (TB) in patients being treated for the disease may be caused by new infections, not acquired resistance, a Chinese study suggests.

Acquired resistance occurs when an organism mutates and becomes progressively resistant to standard therapy.

If the finding is confirmed in future studies, it would alter current beliefs about drug-resistant TB and could lead to major change in methods of controlling the respiratory disease, the researchers said.

This study included 38 patients treated for TB in Shanghai hospitals from 1999 to 2004. Samples taken from the patients before and during treatment revealed that in 87 percent of the patients, the strains of TB in the pre-treatment samples were genetically different from strains in samples taken during treatment.

Further research found that re-infection caused five times as many cases of TB as acquired resistance.

"It was surprising to find a high rate of primary drug-resistant strains among treated patients. This overturned the common belief that drug resistance among treated patients is always acquired," researcher Qian Gao said in a prepared statement.

"Our findings highlight the urgency of accelerating efforts to interrupt the transmission of drug-resistant tuberculosis," Gao said.

The study is published in the March 15 issue of theJournal of Infectious Diseases.

More information

The American Lung Association has more about tuberculosis.

SOURCE: Infectious Diseases Society of America, news release, February 2007