Comparative Study Between PCR Technique And Other Methods Used For Diagnosis of Renal Tuberculosis
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This study was conducted on 64 patients (41 males, 23 females, age 19-56 years) clinically suggested to have renal tuberculosis to investigate the presence of mycobacteria in their urine using Ziehl-Neelsen (ZN) staining, conventional Lowenstein Jensen (Li) culture, BACTEC culture method and polymerase chain reaction (PCR). Three successive morning urine specimens were collected from each patient, decontaminated, concentrated and microscopically examined, cultured on LI media and BACTEC 12B mycobacteria vials. PCR was performed for all urine specimens to detect M. tuberculosis complex using IS 6110 DNA segment as an amplification target, primer F (BM 2002) and primer R (BM T003). Ziehl-Neelsen stained smears were positive in 31/64 patients (48.4%). Conventional cultures on LJ and on BACTEC 12B media gave the same results and each was positive in 39/64 of patients (60.9%). Assuming culture as the reference test, the sensitivity, specificity, positive predictive value and negative predictive value of ZN stained smears vere 66.7%, 80%, 83.9% and 606%, and for PCR were 87.2%, 64%, 79.1% and 79.2% respectively. The results of the study as well as the characteristics of PCR encourage its use for the rapid recognicion of renal tuberculosis although its findings should be interpreted cautiously when clinical picture is not consistent with active tuberculosis.