WHO TB test detects twice as many cases as smear microscopy

The World Health Organization's recommended test for pulmonary tuberculosis, Xpert MTB/RIF, was shown to detect twice as many TB cases than smear microscopy in a study conducted among children in Africa.

The study, conducted at two hospitals in Cape Town, South Africa, was conducted to determine the accuracy of the Xpert MTB/RIF test and its potential as a replacement for smear microscopy as an initial diagnostic measure for HIV-associated TB or multidrug-resistant TB, according to The Lancet.

The two hospitals used in the study were known to be located in areas with both high rates of TB and HIV. Children eligible to take part in the test were aged 15 or younger and had been admitted to the hospital with suspected cases of pulmonary TB.

Sputum samples were taken from 452 children for testing purposes. Of those, 24 percent were determined to be HIV positive. A positive smear for TB was observed in six percent of the children. The Xpert MTB/RIF test determined that 13 percent were infected. The actual rate of infection was later determined to be approximately 16 percent through culture testing.

“MTB/RIF testing of two induced sputum specimens is warranted as the first-line diagnostic test for children with suspected pulmonary [TB],” the researchers said, reports.