Diagnosis of peritoneal tuberculosis by real-time immuno-PCR assay based on detection of a cocktail of Mycobacterium tuberculosis CFP-10 and HspX proteins

Abstract

ABSTRACT Background : Diagnosis of peritoneal TB is difficult owing to unusual clinical manifestations and low sensitivities obtained with most of the available diagnostic modalities. Hence, there is an urgent need to design a reliable and rapid diagnostic test followed by early therapy so as to avoid the complications associated with disease. Research design and methods : We designed a quantitative real-time immuno-PCR (RT-I-PCR) assay to detect a cocktail of Mycobacterium tuberculosis CFP-10 (Rv3874) and HspX (Rv2031c) proteins in clinical samples (ascitic fluids and peritoneal biopsies) of peritoneal TB patients and results were compared with I-PCR/ELISA. Results : A wide range of CFP-10+HspX (0.6 pg/mL to 9.9 ng/mL) was detected in clinical samples of peritoneal TB patients by RT-I-PCR, whereas ELISA exhibited a narrow range (3ng/mL to 11.5 ng/mL). Sensitivities of 81.5% and 65.7%, and specificities of 92.5% and 90%, were obtained in total 78 cases (comprising 38 peritoneal TB and 40 non-TB controls) by RT-I-PCR and I-PCR, respectively. Markedly, sensitivity obtained by RT-I-PCR was significantly higher than I-PCR (p=0.0143) and ELISA (p=0.0005). Conclusions : Our RT-I-PCR revealed good accuracy for the rapid diagnosis of peritoneal TB cases. After further improving the specificity and reducing the cost, this assay may develop into a diagnostic kit.