在高结核病负担地区，使用GeneXpert MTB/RIF检测法对浓缩细针穿刺抽吸物进行结核性淋巴结炎诊断
GeneXpert MTB/RIF Assay for the Diagnosis of Tuberculous Lymphadenitis on Concentrated Fine Needle Aspirates in High Tuberculosis Burden Settings.
作者信息
Tadesse Mulualem, Abebe Gemeda, Abdissa Ketema, Aragaw Dossegnaw, Abdella Kedir, Bekele Alemayehu, Bezabih Mesele, Apers Ludwig, de Jong Bouke C, Rigouts Leen
机构信息
Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia; Mycobacteriology Research Center, Institute of Biotechnology Research, Jimma University, Jimma, Ethiopia; Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia; Mycobacteriology Research Center, Institute of Biotechnology Research, Jimma University, Jimma, Ethiopia.
出版信息
PLoS One. 2015 Sep 14;10(9):e0137471. doi: 10.1371/journal.pone.0137471. eCollection 2015.
INTRODUCTION
The diagnosis of tuberculous lymphadenitis (TBL) remains challenging. The routinely used methods (cytology and smear microscopy) have sub-optimal sensitivity. Recently, WHO recommends GeneXpert to be used as the initial diagnostic test in patients suspected of having extra-pulmonary tuberculosis (EPTB). However, this was a conditional recommendation due to very low-quality evidence available and more studies are needed. In this study we evaluated the performance of Xpert for the diagnosis of TBL on concentrated fine needle aspirates (FNA) in Southwest Ethiopia.
METHODS
FNA was collected from presumptive TBL cases. Two smears were prepared from each aspirate and processed for cytology and conventional microscopy. The remaining aspirate was treated with N-acetyl-L-cysteine-NaOH and centrifuged for 15minutes at 3000g. The concentrated sediment was used for culture and Xpert test. Capilia TB-Neo test was used to differentiate M. tuberculosis complex (MTBC) from non-tuberculous mycobacteria (NTM). Composite bacteriological methods (culture and/or smear microscopy) were considered as a reference standard.
RESULT
Out of 143 enrolled suspects, 64.3% (92/143) were confirmed TBL cases by the composite reference standard (CRS). Xpert detected M. tuberculosis complex (MTBC) in 60.1% (86/143) of the presumptive TBL cases. The sensitivity of Xpert compared to CRS was 87.8% [95% CI: 81.0-94.5] and specificity 91.1% [95% CI: 82.8-99.4]. The sensitivity was 27.8% for smear microscopy and 80% for cytology compared to CRS. Cytology showed the lowest specificity (57.8%). Xpert was positive in 4 out of 45 culture- and smear-negative cases. Among 47 cytomorphologically non-TBL cases, 15 were positive on Xpert. More than half of Xpert-positive cases were in the range of very low cut-off threshold values (28<Ct<38). Resistance to rifampicin was identified in 4.7% (4/86) of Xpert-positive cases.
CONCLUSION
Xpert test showed a high sensitivity and specificity for the diagnosis of TBL on concentrated FNA samples. In addition, Xpert offered rapid detection of rifampicin-resistant M. tuberculosis strains from lymph node aspirates.
引言
结核性淋巴结炎（TBL）的诊断仍然具有挑战性。常规使用的方法（细胞学和涂片显微镜检查）敏感性欠佳。最近，世界卫生组织建议将GeneXpert用作疑似肺外结核（EPTB）患者的初始诊断测试。然而，由于现有证据质量极低，这是一项有条件的建议，还需要更多研究。在本研究中，我们评估了Xpert在埃塞俄比亚西南部对经浓缩的细针穿刺抽吸物（FNA）进行TBL诊断的性能。
方法
从疑似TBL病例中收集FNA。每份抽吸物制备两张涂片，用于细胞学检查和传统显微镜检查。将剩余的抽吸物用N-乙酰-L-半胱氨酸-氢氧化钠处理，并在3000g下离心15分钟。将浓缩沉淀物用于培养和Xpert检测。使用Capilia TB-Neo检测来区分结核分枝杆菌复合群（MTBC）和非结核分枝杆菌（NTM）。综合细菌学方法（培养和/或涂片显微镜检查）被视为参考标准。
结果
在143名纳入的疑似病例中，64.3%（92/143）通过综合参考标准（CRS）确诊为TBL病例。Xpert在60.1%（86/143）的疑似TBL病例中检测到结核分枝杆菌复合群（MTBC）。与CRS相比，Xpert的敏感性为87.8%[95%置信区间：81.0 - 94.5]，特异性为91.1%[95%置信区间：82.8 - 99.4]。与CRS相比，涂片显微镜检查的敏感性为27.8%，细胞学检查的敏感性为80%。细胞学检查显示特异性最低（57.8%）。在45例培养和涂片均为阴性的病例中，有4例Xpert检测呈阳性。在47例细胞形态学上非TBL的病例中，有15例Xpert检测呈阳性。超过一半的Xpert阳性病例处于非常低的临界阈值范围内（28 < Ct < 38）。在Xpert阳性病例中，4.7%（4/86）被鉴定为对利福平耐药。
结论
Xpert检测对经浓缩的FNA样本进行TBL诊断显示出高敏感性和特异性。此外，Xpert能够快速从淋巴结抽吸物中检测出耐利福平的结核分枝杆菌菌株。
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