Cerebrospinal fluid IgG against TB-SA for diagnosis of tuberculous meningitis

W. Zhang, X.-X. Guo, X.-F. Wang, M.-S. Wang

Department of Quality Control, Binzhou Central Blood Center, Binzhou, China. 13789821006@163.com

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• Infectious Diseases

OBJECTIVE: A commercial enzyme linked immunosorbent assay (ELISA) detecting cerebrospinal fluid (CSF) IgG against TB-SA (CYPCO TB (IgG) ELISA assay) for diagnosing tuberculous meningitis (TBM) was evaluated retrospectively. Meanwhile, Pandy test was introduced to grade patients, improving its role in the detection of TBM.

PATIENTS AND METHODS: 187 consecutive cases with determined diagnosis were enrolled and divided into TBM group and Non-TBM group. CSFs were collected and sent for Pandy test, cytology, routine biochemistry tests, acid-fast smear and mycobacterial culture. The diagnostic parameters of the ELISA assay were evaluated. Differences in sensitivity between groups were estimated using a McNemar’s test.

RESULTS: The overall sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio of the ELISA assay were 31.6% (95% CI: 21.0-44.5%), 97.7% (95% CI: 93.4-99.2%), 85.8, 76.5, 13.7 and 0.7, respectively. McNemar’s test showed the sensitivity of CYPCO TB (IgG) ELISA assay significantly positively correlated with the results of Pandy test (p < 0.05). The ten Pandy test “3+” patients were all TBM. Therefore, patients with “3+” Pandy test are highly suspected of TBM.

CONCLUSIONS: The commercial CYPCO TB (IgG) ELISA assay is able to rapidly confirm a diagnosis of TBM. The sensitivity of the ELISA assay is significantly positively correlated with the results of Pandy test. Patients with “3+” Pandy test are highly suspected of TBM.

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