A comparative evaluation of enzyme linked immunospot assay and IS6110 polymerase chain reaction for early diagnosis of tuberculous meningitis

Abstract

Objective To establish an early diagnostic test for tuberculous meningitis (TBM) with good sensitivity and specificity. Methods Twenty-five patients with a clinical diagnosis of TBM and 49 controls, including 27 patients with other infectious diseases of central nervous system and 22 patients with noninfectious neurological diseases, were enrolled in our research. We simultaneously detected antimycobacterium bovis BCG IgG secreting cells in both cerebral spinal fluid (CSF) and peripheral blood (PBL)by enzyme linked immunospot assay(ELISPOT),repeated insertion sequence IS6110 specific for mycobacterium tuberculosis in CSF by PCR and anti-BCG IgG titre in both CSF and PBL by enzyme linked immunosorbent assay(ELISA).Results The sensitivity of ELISPOT was 84.0%,much higher than that of PCR(75.0%)and ELISA(52.3%).The specificities of the three tests were 91.8%,93.7%and 91.8%respectively.The numbers of CSF cells secreting anti-BCG IgG tested by ELISPOT were even higher in the early phase of TBM, but declined along with the disease progressing(t=-3.183,P=0.008),which allowed an early diagnosis to be made. Conclusion ELISPOT technique is proved to be the most valuable test for the early diagnosis of TBM. Key words: Tuberculosis, meningeal; Enzyme-linked immunosorbent assay; Polymerase chain reaction