The Role of Molecular Techniques for the Detection of Mycobacterium Tuberculosis Complex in Paraffin-embedded Biopsies.

INTRODUCTION

Extrapulmonary tuberculosis (EPTB) is increasingly frequent in developed countries. When it is not clinically suspected, samples are not collected for culture and the only material available is a tissue paraffin block.

OBJECTIVE

The aim of this study was to evaluate FluoroType MTB (FT-MTB) and GenoType MTBDRplus methods for the detection of Mycobaterium tuberculosis complex in paraffin-embedded biopsies comparing the results to tuberculosis diagnosis.

METHODOLOGY

A total of 17 paraffin-embedded tissues from different locations revealing granulomas were referred to the Mycobacteriology Laboratory and FT-MTB and GenoType MTBDRplus methods were performed. EPTB diagnosis was reached based on histologically compatible lesions, response to treatment and absence of alternative diagnosis. This case definition was considered gold standard for the assessment of the 2 molecular techniques performance.

RESULTS

Of the 17 individuals included in the study, 10 were clinically classified as EPTB and in 7 cases tuberculosis was ruled out. Of the 10 patients classified as EPTB, 6 (60%) obtained both FT-MTB and MTBDRplus positive results. Sensitivity and specificity were 60% and 71.4%, and 60% and 85.7% for FT-MTB and MTBDRplus, respectively.

CONCLUSION

Molecular techniques might be useful tools for detection of Mycobaterium tuberculosis complex in paraffin-embedded biopsies especially when there is no sample available for culture.