Diagnosis of osteoarticular tuberculosis: multi-targeted loop-mediated isothermal amplification assay versus multiplex-PCR

Aim: Diagnosis of osteoarticular tuberculosis (OATB) is quite challenging and there is an urgent need to design a prompt and precise diagnostic test. Methods: We developed a multi-targeted loop-mediated isothermal amplification (LAMP) assay using mpt64 (Rv1980c) and pstS1 (Rv0934) targets for the detection of Mycobacterium tuberculosis in OATB patients. Results: The sensitivities of 100 and 82.4% were obtained in confirmed (n = 10) and suspected (n = 57) OATB cases, respectively by multi-targeted LAMP with a specificity of 96.9% (n = 33). Moreover, the sensitivities attained by multi-targeted LAMP in total OATB cases were significantly higher (p < 0.05-0.01) than multiplex-PCR (mpt64 + pstS1) and GeneXpert assay. Conclusion: Our LAMP is simple, reliable and cost-effective method, which may develop into an attractive diagnostic kit for early detection of OATB cases. Lay abstract Diagnosis of osteoarticular tuberculosis (OATB) or bone and joint TB caused by Mycobacterium tuberculosis (Mtb) is quite difficult owing to the low bacterial load present in OATB specimens, and difficulty of obtaining specimens since Mtb bacilli are only present deep inside the tissues. Mostly, diagnosis of OATB relies on clinical findings and imaging, which often mimic other pus-producing microbial infections and inflammatory arthritis, while the conventional bacteriological tests (smear/culture) almost fail. Therefore, we developed a multi-targeted loop-mediated isothermal amplification (LAMP) assay for early detection of OATB cases, which showed superiority over multiplex-PCR and GeneXpert assay. Overall, our LAMP is straightforward, accurate and low-cost assay that may lead to the development of a diagnostic kit for routine use.

Automated summary

The study developed a multi-targeted LAMP testing method for the early detection of osteoarticular tuberculosis cases, showing superiority over other testing methods. It is a simple, reliable, and cost-effective diagnostic tool.