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Rapid Tuberculosis Diagnostic Methods Inaccurate Alone

Stepwise approach seen yielding best results for a rapid preliminary diagnosis of tuberculosis

MONDAY, April 4 (HealthDay News) -- Rapid microbial and immunological diagnostic methods are not accurate enough to diagnose or exclude pulmonary tuberculosis, according to a study published online March 21 in the Journal of Internal Medicine.

Claudia Jafari, M.D., from the Research Center Borstel in Germany, and colleagues evaluated different methods used for an initial treatment decision in 135 individuals with suspected pulmonary tuberculosis. A specific algorithm including initial smear microscopy and M. tuberculosis-specific nucleic acid amplification from sputum, was used to enroll individuals with suspected tuberculosis. Tuberculin skin testing, bronchoscopy with transbronchial biopsies, and interferon-γ release assays (IGRAs) in peripheral blood and bronchoalveolar lavage (BAL) fluid were performed in cases of negative test results.

The researchers identified 42 cases of tuberculosis, 10 cases of non-tuberculous mycobacteria pulmonary infection/colonization, and 84 with a different diagnosis. Sputum microscopy had sensitivity of 41 percent and specificity of 99 percent. BAL nucleic acid amplification had sensitivity of 31 percent and specificity of 98 percent. M. tuberculosis-specific BAL fluid IGRAs had 92 percent sensitivity and 87 percent specificity for the tuberculosis diagnosis in patients with acid-fast bacilli smear-negative tuberculosis.

"The key finding of the study was that none of the evaluated methods alone was able to reliably diagnose or exclude tuberculosis," the authors write. "A stepwise diagnostic approach may yield the best results for a rapid preliminary diagnosis of tuberculosis, justifying treatment initiation while the results of M. tuberculosis cultures are pending."

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