Identification of mycobacterial MPT-64 and ESAT-6 proteins in urogenital tuberculosis patients by real-time immuno-PCR

Aim: Diagnosis of urogenital tuberculosis (UGTB) is difficult and there is an immediate need to develop a reliable diagnostic test. Methods: A real-time immuno-PCR (RT-I-PCR) was developed to identify a cocktail of MPT-64 + ESAT-6 in both male/female UGTB patients comprising five confirmed cases, 40 clinically suspected cases and 37 non-TB controls, from whom mid-stream urine specimens were collected, while endometrial biopsies of female patients were obtained on day 1 of their menstrual cycle. Results obtained by RT-I-PCR were compared with I-PCR/ELISA and GeneXpert. Results: A wide range (500 fg/ml-10 ng/ml) of MPT-64 + ESAT-6 was detected in UGTB specimens by RT-I-PCR, although ELISA showed a narrow range (2.5-11 ng/ml). Sensitivities of 80% and 82.2% were obtained by RT-I-PCR in clinically suspected and total UGTB cases, respectively, whereas 94.6% specificity was obtained. Concurrently, RT-I-PCR revealed significantly higher (p < 0.05-0.001) sensitivity than I-PCR/ELISA and GeneXpert. Conclusion: After improving the specificity, the authors may develop RT-I-PCR into a diagnostic kit. Plain language summary Urogenital tuberculosis (UGTB) involves infection of the urinary tract and genital organs of male/female patients by Mycobacterium tuberculosis bacteria. Delayed diagnosis and therapy of UGTB lead to infertility and kidney failure. The routine tests used to detect the bacteria are not very sensitive due to low levels of bacteria present in UGTB specimens. Moreover, most nucleic acid amplification tests, such as PCR tests, give false-positive and false-negative results. The authors designed a real-time immuno-PCR test for detecting a cocktail of M. tuberculosis proteins in UGTB patients that revealed quite promising results, which were superior to immuno-PCR/ELISA and GeneXpert tests. After further improvement in the specificity and reduction of the price, this real-time immuno-PCR test could be used in routine diagnosis.