Quick test kit for tuberculous meningitis
doi:10.1038/nindia.2007.30 Published online 3 November 2007
There has been a rising trend of tuberculous meningitis (TBM), a common manifestation of extra-pulmonary TB, in developing countries such as India in the past two decades. Its detection is difficult because of the various forms in which it appears clinically.
It is also difficult for doctors to confirm TBM due to a lack of rapid, sensitive, and specific tests. Although conventional bacterial culture is the gold standard for diagnosis, the inherent time limitation of the culture-based test, limits its value.
Polymerase chain reaction (PCR) is considered to be one of the most specific diagnostic methods. Many commercial polymerase chain reaction (PCR) kits are in use for rapid diagnosis of TBM, but studies show that they have low sensitivity.
The high costs involved for commercial assays do not make them an affordable option for developing countries. The research team evaluated an in-house PCR method for the diagnosis of TBM. The study was performed using primers directed against the insertion sequence IS6110 gene, for the detection of Mycobacterium tuberculosis in samples available from a hospital.
Though several M. tuberculosis-specific DNA sequences were evaluated in different laboratories, the researchers targeted IS6110 gene for PCR because of its repetitive nature in the M. tuberculosis genome. The assay detected the presence of M. tuberculosis DNA in 91.4% cases of confirmed TBM and in 62.5% cases of clinically diagnosed TBM which otherwise were negative for mycobacterial culture, but had a clinical index of suspicion for TBM. The researchers say this could be adopted as a method of choice for the rapid diagnosis of mycobacterial infections in high suspicion cases.
The authors of this work are from: Biochemistry Research Laboratory, Central India Institute of Medical Sciences, Nagpur, India; Environmental Genomics Unit, National Enviromental Engineering Research Institute, Nehru Marg, Nagpur, India.
- Deshpande, P. S.et al. Evaluation of the IS6110 PCR assay for the rapid diagnosis of tuberculous meningitis. Cerebrospinal Fluid Res. doi:10.1186/1743-8454-4-10 (2007).