Can tissue PCR augment the diagnostic accuracy in genitourinary tract tuberculosis?

Conventional methods like smear and culture for Mycobacterium tuberculosis are of limited sensitivity and specificity. Histopathological examination (HPE) for the tissues obtained gives inconclusive diagnosis in the absence of caseous necrosis or stained acid-fast bacilli. This study was conducted to determine the utility of tissue PCR for diagnosing tuberculosis of the genitourinary tract (GUTB) and its comparative evaluation with HPE.

A prospective study was conducted from January 2006 to August 2009 with 78 tissue specimens (renal, prostate, epididymis, penile and soft tissue) from patients with clinically suspected GUTB. All the samples were processed for both PCR and histopathology.

In 68 (87.1%) samples, results for both PCR and HPE were coinciding. False positivity and false negativity was observed in 5.1% (4/78) and 7.6% (6/78) samples, respectively. With HPE as the gold standard, PCR has shown sensitivity of 87.5% (95% CI 80.1; 91.9) and specificity of 86.7% (95% CI 74.9; 93.8) and positive agreement between two tests was observed as significant (0.7). PCR results were obtained within a mean period of 3.4 days while those of HPE were obtained in 7.2 days.

Tissue PCR is a sensitive and specific method for obtaining early and timely diagnosis of GUTB. Application of tissue PCR results can augment the diagnostic accuracy in histopathologically labelled granulomatous inflammations.