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New test returned rapid diagnosis for pediatric TB

Rapid diagnosis of pediatric pulmonary tuberculosis in primary care can be achieved using the Xpert MTB/RIF on respiratory secretions, according to recent study findings published in The Lancet Global Health.

“There has been a perception among health care workers that rapid diagnosis of TB in children wouldn’t be possible in primary care, but this study disproves that view,” Heather J. Zar, MD, PhD, of the University of Cape Town and Red Cross War Memorial Children’s Hospital, said in a press release. “Given our results, widespread adoption of rapid testing for TB and drug resistance in children may substantially improve public health without greatly increasing costs.”

The prospective study included 384 children aged younger than 15 years with suspected pulmonary TB who had at least one induced sputum specimen and one nasopharyngeal aspirate. Xpert MTB/RIF Assay (Cepheid) returns results in as soon as 24 hours.

Researchers found that 1% of children had a positive smear, 7% had a positive Xpert MTB/RIF Assay and 8% had a positive cultures result. Sixteen of 28 culture-confirmed cases were detected by Xpert MTB/RIF Assay on two induced sputum samples (sensitivity, 57.1%; 95% CI, 39.1-73.5), and the test detected 11 of 28 culture-confirmed cases on two nasopharyngeal aspirates (sensitivity, 39.3%; 95% CI, 23.6-57.6). Specificity on induced sputum was 98.9% (95% CI, 96.9-99.6) and 99.3% (95% CI, 97.4-99.8) on nasopharyngeal aspirates for Xpert MTB/RIF Assay.

In an accompanying editorial, Annelies Van Rie, MD, PhD, of the School of Public Health at the University of North Carolina, said the assay has proved useful in immunocompromised adults, but no data have been published on children with HIV.

“The most compelling reason might be that suspicion of drug-resistant TB,” she said. “In such cases, rapid knowledge of the presence of rifampicin resistance can inform which children should receive extended treatment with potentially toxic second-line drugs. Despite the crucial need for rapid, accurate, and affordable diagnostics for pulmonary TB in young children, it seems unlikely that Xpert MTB/RIF will be the game changer that high-burden countries are desperately waiting for.”

For more information:

• Van Rie A. Lancet Global Health. 2013;doi:10.1016/S2214-109X(13)70049-4.
• Zar HJ. Lancet Global Health. 2013;doi:10.1016/S2214-109X(13)70036-6.

Disclosure: Zar and Van Rie report no relevant financial disclosures.