Comparison of Nested-PCR technique and culture method in detection of Mycobacterium tuberculosis from patients suspected to genitourinary tuberculosis

Abstract

The aim of the present study was to evaluate the diagnostic value of nested PCR in genitourinary tuberculosis (GUTB) compared with acid fast staining and culture method. In total 200 urine samples from suspected cases of GUTB were collected during the period of study. Urine pellets were used for smear preparation, culture and DNA extraction by ether-chloroform method. Nested PCR was performed according to standard protocol using primers based on IS6110 gene fragment. The results obtained by PCR were compared with those obtained by standard acid-fast bacilli stain and culture method. Based on obtained results, the positivity rate of urine samples in this study was 5.0% by using culture and PCR methods and 2.5% for acid fast staining. Four out of total samples showed positive results in all three methods (2%). The sensitivity of PCR in this study was estimated as high as culture equal to 100%, while the sensitivity for direct smear staining was 41.6%. In conclusion, the obtained rate of GUTB in our study was 5.0%. Since the detection rate of culture and nested PCR was identical, we could suggest PCR as a rapid alternative to culture especially for confirmed cases of GUTB.