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

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 diagnostic test so that an early therapy is initiated. 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 (3 ng/mL to 11.5 ng/mL). Sensitivities of 81.5% and 65.7% and specificities of 92.5% and 90% were obtained in a total of 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.