Abstract:

Objective To compare the performance of common laboratory techniques in the diagnosis of tuberculous meningitis (TBM) in order to improve early diagnosis of TBM.Methods Five techniques including BACTEC MGIT 960 liquid culture method (MGIT 960 method), modified acid-fast staining (MZN method), GeneXpert MTB/RIF (GeneXpert method), fluorescent probe polymerase chain method (PCR-fluorescence probe method), and tuberculosis infection T cell spot test (T-SPOT.TB) were conducted with cerebrospinal fluids of 224 adult suspected TBM patients who admitted in Xi’an Chest Hospital from January 2017 to April 2018. There were 71 patients in the TBM group (36 in the confirmed group, 23 in the strongly probable group, and 12 in the possible group) and 33 in the non-TBM group. Performance of the above five laboratory techniques for diagnosing TBM were assessed. The values of bacteriological method (MGIT 960 and MZN methods), molecular biology method (GeneXpert and PCR-fluorescence probe method), immunology method (T-SPOT.TB), and combination of all five techniques in early diagnosis of TBM were compared.Results Taking the clinical diagnosis results as standard, the specificity and positive predictive value of the five detection techniques for TBM diagnosis were all 100.0%. The sensitivity of MGIT 960, MZN, GeneXpert, PCR-fluorescence probe and T-SPOT.TB method were 19.7% (14/71), 26.8% (19/71), 42.3% (30/71), 35.2% (25/71), and 29.6% (21/71), respectively. The sensitivity of the GeneXpert method and the PCR-fluorescence probe method was higher than that of the MGIT 960 method, and the differences were statistically significant (χ ²=8.43, P=0.004; χ ²=4.28, P=0.039). The sensitivity of the bacteriological method, molecular biology method, the immunology method, and the combined method were 31.0% (22/71), 50.7% (36/71), 29.6% (21/71), and 73.2% (52/71), respectively. The sensitivity of the molecular biology method and the combined diagnosis method were higher than that of the bacteriological method, and the differences were statistically significant (χ ²=5.71, P=0.017; χ ²=73.20, P=0.000). Conclusion In the early diagnosis of TBM, the sensitivity of GeneXpert and PCR-fluorescence probe method is higher compared with MGIT 960 method. The combined detection of experimental methods can improve the sensitivity of TBM diagnosis. Compared with the bacteriological method, the sensitivity of the biological method and combined diagnosis method is higher.

Key words: Tuberculosis, meningeal, Clinical laboratory techniques, Early diagnosis, Comparative study, Data interpretation, statistical