Clinical, Laboratory and Radiological Correlates of Xpert MTB/RIF Assay Study in Cerebrospinal Fluid in CNS...

Cerebrospinal fluid (CSF) Xpert MTB/RIF assay is an initial test for the diagnosis of tuberculous meningitis (TBM). Nevertheless, it is not very clear which of the factors govern CSF-Gene Xpert/MTB positivity.

Hence, we aimed to assess the relationship, if any, between the clinical, laboratory and radiological parameters of the central nervous system (CNS) tuberculosis patients and the Gene Xpert study in CSF in such patients.

First, we studied 200 patients with CNS tuberculosis according to the case definition, and subsequently, we performed a Gene Xpert study on the CSF of these patients. Then, we correlated the clinical, radiological, and CSF criteria with the Gene Xpert positivity using the univariate binary logistic regression method via SPSS 20 (P-value <0.05).

Seventy-five (37.5%) patients (57.3% females) of median 24 years of age, were CSF-Gene Xpert/MTB-positive and 125 (62.5%) patients were negative. The mean duration of illness (P = 0.017), weight loss or failure to thrive (P < 0.001), loss of consciousness or seizure (P = 0.001), signs of meningeal irritation (P = 0.027), stage III of TBM (P < 0.001), evidence of dissemination (P = 0.003), basal exudates (P = 0.004), hydrocephalus (P = 0.018), CSF lymphocytic predominance (P < 0.001), and reduced CSF glucose (P = 0.011) correlated significantly with positive the Gene Xpert/MTB results. Also, Gene Xpert had a sensitivity of 80% and a specificity of 74.84% against culture Xpert.

Xpert MTB/RIF might be more useful in the later stages of the disease and those with more severe disease.