Rapid diagnosis of genitourinary tuberculosis by polymerase chain reactionand non-radioactive DNA hybridization

Objective: To establish a polymerase chain reaction (PCR) assay for the rap id detection and identification of mycobacteria in urine, and to assess the value of such assay in routine laboratory diagnosis of genitourinary tuber culosis. Materials and Methods: Urine specimens from 1000 patients with clinical sus picion of urinary tuberculosis were examined. Two assays for the detection and identification of Mycobacterium tuberculosis (M. tuberculosis) complex and mycobacteria other than tuberculosis (MOTT) by non-radioactive DNA hybr idization of PCR-product were applied, The first assay used PCR primers and probe derived from M. tuberculosis species-specific DNA insertion sequence , IS6110. The second utilized mycobacterium genus-specific sequence encodin g ribosomal ribonucleic acid (16S rRNA). The results obtained by PCR were c ompared with those obtained by standard microbiological methods, acid-fast bacilli (AFB) stain and culture. Results: Compared with cultures, the sensitivity of AFB staining was 52.07% and the specificity was 96.7%. In comparison to the results of culture, th e overall sensitivity and specificity of the IS6110-PCR assay was 95.59% an d 98.12% respectively. While the corresponding results for the 16S rRNA gen e-PCR were 87.05% and 98.9%. Conclusion: The high sensitivity and specificity in addition to the potenti al for rapid detection of mycobacteria, makes this test a useful tool in th e clinical management of mycobacterial infection in urine. Urine specimens may contain M. tuberculosis and/or other mycobacteria; therefore, there are advantages in using genus-specific primers in parallel with species-specif ic primers in PCR assay.