Detection of Mycobacterial Infection in Paraffin-Embedded Pathologic Tissues by DNA Polymerase Chain Reaction: Comparison with Conventional Histochemical Stain

Abstract

Objectives. Tuberculosis caused by Mycobacterium tuberculosis is one of the most common infectious diseases worldwide. Pathologic confirmation by demonstrating mycobacterial bacillus in tissue section using histochemical stain or culture is the traditional diagnostic method. However, the diagnostic rate by both histochemical stain and culture is low. Polymerase chain reaction (PCR) is able to detect trace amounts of nucleic acid in paraffin sections. We detected mycobacterial DNA in pathological samples by PCR and compared the results with those of histochemical stain and culture. Methods. Formalin-fixed paraffin-embedded tissue sections of 16 acid-fast positive and 17 acid- fast negative tissue samples showing granulomatous inflammation were retrieved retrospectively for PCR study. Results. PCR detected mycobacterial DNA in 14 out of 16 acid-fast positive and 14 out of 17 acid- fast negative samples. The sensitivity and specificity for detecting Mycobacterium by PCR were much higher than acid-fast stain and culture. Conclusions. PCR method was very useful in detecting mycobacterial infection in pathologic sections. We believe that the establishment of the PCR method in the department of pathology will improve the quality of clinical and pathologic diagnosis of tuberculosis.