Evaluation of two commercial real-time PCR assays, conventional PCR and acid fast bacilli stain for detection of Mycobacterium tuberculosis complex in formalin-fixed, paraffin-embedded tissue

Abstract

Mycobacterium tuberculosis complex (MTBC) is a group of closely related organisms causing tuberculosis, which is the second-most common cause of death from infectious diseases worldwide. Several methods for detecting MTBC are available and different in sensitivity, specificity, tools and costs. We used four methods comprising histochemistry stain for acid fast bacilli (AFB stain), conventional polymerase chain reaction (C-PCR) and two commercial molecular assays, artus® Mycobac. Diff. LC PCR Kit (artus® Mycobac) and abTES™MTB qPCR I KIT (abTES™MTB) and compared the sensitivity in 80 paraffin-embedded tissue samples that showed histomorphology suspected of tuberculous infection. Positive results were detected in 41 samples (51.2 %) by C-PCR, 40 samples (50.0 %) by abTES™MTB, 30 samples (37.5 %) by artus® Mycobac and 27 samples (33.8 %) by AFB stain. There was no significant difference for the sensitivity in the detection of MTBC by C-PCR and abTES™MTB.  Good agreement between these methods (K=0.625 and 95% CI = 0.454-0.796) was observed.. Both methods showed significantly higher sensitivity than artus® Mycobac and AFB stain (P < 0.005).