Krishnakumariamma Krishnapriya, Ellappan Kalaiarasan, Muthuraj Muthaiah, Tamilarasu Kadhiravan, Kumar Saka Vinod, Joseph Noyal Mariya
Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India.
Intermediate Reference Laboratory, Government Hospital for Chest Diseases, Pondicherry, India.
Indian J Med Microbiol. 2023 Mar-Apr;42:7-11. doi: 10.1016/j.ijmmb.2022.12.012. Epub 2023 Jan 19.
We aimed this study to standardize real time - polymerase chain reaction (RT-PCR) for the detection of Mycobacterium tuberculosis (Mtb) in cerebrospinal fluid (CSF) samples and compare its diagnostic performance with GeneXpert (Xpert), Mycobacteria Growth Indicator Tube (MGIT) and Multiplex PCR (MPCR) for tuberculous meningitis (TBM).
A total of 217 CSF samples were obtained from patients with suspected TBM during the study period between January 2019 and December 2021. The optimal cycle threshold (CT) of RT-PCR was determined by comparing different gene targets of Mtb (IS6110, 16SrRNA, HSP65 and Ag85B). Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) was determined for RT-PCR, Xpert, MGIT960 and MPCR. Diagnostic accuracy of these assays was compared by using clinical diagnosis as reference standard.
IS6110RT-PCR was found to be highly sensitive as compared to other gene targets. Sensitivities of IS6110RT-PCR, MPCR, Xpert and MGIT against a reference standard of definite, probable and possible TBM were 36.7%, 21.1%, 16.7% and 6.7%, respectively; specificities were 97.6%, 100%, 100% and 100%, respectively. Xpert, RT-PCR, MPCR and MGIT960 detected 6.91% (n = 15), 5.99% (n = 13), 5.99% (n = 13) and 2.76% (n = 6) of definite TBM, respectively. RT-PCR detected 6.45% (n = 14) and 2.76% (n = 6) of possible TBM and probable TBM, respectively and MPCR detected 1.38% (n = 3) of possible and probable TBM each.
IS6110RT-PCR is highly sensitive for primary screening of suspected TB cases, which may help clinicians to start appropriate patient's treatment with clinical suspicion of TBM.
本研究旨在规范用于检测脑脊液（CSF）样本中结核分枝杆菌（Mtb）的实时聚合酶链反应（RT-PCR），并将其诊断性能与用于结核性脑膜炎（TBM）诊断的GeneXpert（Xpert）、分枝杆菌生长指示管（MGIT）和多重PCR（MPCR）进行比较。
在2019年1月至2021年12月的研究期间，共从疑似TBM患者中获取了217份CSF样本。通过比较Mtb的不同基因靶点（IS6110、16SrRNA、HSP65和Ag85B）确定RT-PCR的最佳循环阈值（CT）。测定RT-PCR、Xpert、MGIT960和MPCR的敏感性、特异性、阳性预测值（PPV）和阴性预测值（NPV）。以临床诊断为参考标准比较这些检测方法的诊断准确性。
与其他基因靶点相比，发现IS6110 RT-PCR具有高度敏感性。IS6110 RT-PCR、MPCR、Xpert和MGIT针对明确、可能和疑似TBM参考标准的敏感性分别为36.7%、21.1%、16.7%和6.7%；特异性分别为97.6%、100%、100%和100%。Xpert、RT-PCR、MPCR和MGIT960分别检测出6.91%（n = 15）、5.99%（n = 13）、5.99%（n = 13）和2.76%（n = 6）的明确TBM。RT-PCR分别检测出6.45%（n = 14）的疑似TBM和2.76%（n = 6）的可能TBM，MPCR分别检测出1.38%（n = 3）的可能和疑似TBM。
IS6110 RT-PCR对疑似结核病病例的初步筛查具有高度敏感性，这可能有助于临床医生在临床怀疑TBM时开始对患者进行适当治疗。
