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. |
