Identification of Mycobacterium tuberculosis in the cerebrospinal fluid of patients with meningitis using nested PCR.

Abstract

Tuberculous meningitis (TBM) is the most severe form of tuberculosis. It is caused by Mycobacterium tuberculosis(M.tuberculosis; MT) and it is very difficult to diagnose. The symptoms are similar to other infectious neurological diseases, such as neurocysticercosis, neuroborreliosis, or herpes viral infection. The aim of this study was to identify tuberculosis(TB) in cases of meningitis with clinical and laboratory evidence suggestive of TBM, and to confirm our findings with molecular tests for TB infection. We recruited patients with neurological symptoms who were examined at the neurology services of Hospitals of Instituto Mexicano del Seguro Social(IMSS) in MexicoCity. A total of 144consecutive patients with suggestive infectious meningitis were initially included; 94cases of meningitis with clinical and laboratory evidence suggestive of TBM were included, but only50 of these cases fulfilled the criteria for probable TBM. As the controls, we included 50cases of meningitis with clinical and laboratory evidence suggestive of non-TBM. Cerebrospinal fluid(CSF) was collected from all 100patients (cases and controls) and tested for TB by multiplex and nested PCR analyses. Nested PCR detected 0.1fg of M.tuberculosis DNA. TB infection was confirmed with molecular tests in 49patients from the 50cases suggestive of TBM and in 1of the50non-TBM cases. The analysis exhibited a sensitivity of98.0%, a specificity of 92.0%, a positive predictive value of88.0% and a negative predictive value of98.0%. The use CSF for the analyses proved to be effective for the rapid diagnosis of TBM using a developed system of multiplex and nested PCR analyses in patients presenting neurological symptoms.