Efficacy of real-time polymerase chain reaction for rapid diagnosis of endobronchial tuberculosis

Abstract

The definitive diagnosis of endobronchial tuberculosis (EBTB) is challenging because the disease manifests in various non-specific ways, and acid-fast bacilli (AFB) are often undetectable by sputum smear. The objective of this study was to evaluate the efficacy of real-time PCR of bronchoscopic biopsy specimens for the diagnosis of EBTB. Real-time PCR amplification of Mycobacterium tuberculosis DNA in biopsy tissue from EBTB patients was performed prospectively. Diagnostic yields were compared for real-time PCR and for auramine O-stained sputum smears and bronchial brush smears. Whether diagnostic yield depended on bronchoscopic subtype of EBTB was also evaluated. Diagnostic yields were 4.1% (3/74) for sputum smear, 39.2% (29/74) for bronchial brush smear, and 89.2% (66/74) for real-time PCR. Real-time PCR melting curve analysis showed significantly higher yields than did AFB staining of bronchial brush smears for granular and caseating EBTB (p<0.01). Real-time PCR detection of M. tuberculosis DNA in EBTB biopsy tissue is more sensitive than sputum smear and bronchial brush smear, including at early disease stages. This PCR method may be a useful adjunct to culture- and smear-based techniques to allow more rapid EBTB diagnosis and timelier treatment.