Bridging the gap between PCR detection of Mycobacterium tuberculosis complex and tuberculosis diagnosis

The growing demand for rapid diagnosis of tuberculosis (TB) has led to the incorporation of nucleic acid amplification (NAA) tests in case definitions. The objective of this study was to evaluate the contribution of a real-time polymerase chain reaction (PCR) assay in providing a result predictive of a confirmed TB case. Respiratory and extra-pulmonary specimens (n = 308) were subjected to NAA, culture and smear microscopy. Qualitative PCR assessment, translated by an increase in NAA cycles, disregarding template copy number, resulted in an increase in confirmed cases, helping to bridge the gap between the test's analytical performance and its actual performance in TB diagnosis.