Evaluating the role of Mycobacterium tuberculosis PCR in ruling out active tuberculosis.

Laboratory algorithms using Acid-Fast Bacilli staining and Mycobacterium tuberculosis (Mtb) polymerase chain reaction (PCR) are often used to remove isolation precautions. A retrospective case review of 52 patients with culture-confirmed pulmonary Mtb revealed 4 subjects with negative sputum Acid-Fast Bacilli smears and negative Mtb PCRs. All had significant risk factors for Mtb and had a positive interferon-gamma release assay.