Urine PCR evaluation to diagnose pulmonary tuberculosis

Culture and specific staining (including Zeil-Nelson and fluorescent methods) are standard measures for the diagnosis of tuberculosis (TB). These methods are time-consuming and sometimes have a low level of accuracy. In addition, in some cases obtaining samples for smear and culture involves invasive procedures; while in other cases there is no suitable sample for evaluation. Therefore, there is a need for faster and more accurate diagnostic methods.

The current study investigated the diagnostic value of tuberculosis-polymerase chain reaction (TB-PCR) of urine in the diagnosis of pulmonary tuberculosis (PTB).

This case-control study included; 77 proven pulmonary tuberculosis cases (according to the national TB protocol), and 30 subjects who were completely healthy. The urine samples (50 mL) were mixed with 0.5 mL Ethylene diamine tetraacetic acid. DNA extraction and PCR testing were performed on all blood samples using SI 6110 primers. Mycobacterium tuberculosis was also cultivated in the sputum and urine samples of the patients.

Results of the current study indicated that 48 (62.3%) patients out of 77 had a positive sputum culture. Urine cultures and acid-fast smears were negative. Urine PCR-TB was positive in 48.0% (37/77) of the patients. The specific TBPCR complex was positive in 56.2% (27/48) of the positive cultures and 34.4% (10/29) of the negative culture PTB patients. The control group had negative urine PCR (sensitivity 56.2% and specificity 100%).

With regard to the ease of urine sample preparation and the 100% specificity the PCR method, performing urine PCR could be used as a diagnostic aid in PTB cases obtaining sputum samples is problematic.