National Clinical Laboratory on Tuberculosis, Beijing Key Laboratory on Drug-Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Institute, Beijing, China.
Beijing Key Laboratory for Pediatric Diseases of Otolaryngology, Head and Neck Surgery, MOE Key Laboratory of Major Diseases in Children, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
Biomed Res Int. 2018 Apr 1;2018:1514381. doi: 10.1155/2018/1514381. eCollection 2018.
GeneXpert MTB/RIF (Xpert) assay has been endorsed for the diagnosis of pulmonary TB due to its high sensitivity and specificity for culture positive TB. There is no doubt that Xpert could not be more sensitive than mycobacterial culture, while the positive rate of Xpert among sputum samples was higher than that of mycobacterial culture in our laboratory. We therefore carried out a prospective study to determine a potential explanation for this unexpected result regarding the clinical use of Xpert. Overall, a total of 558 patients meeting inclusion criteria were enrolled in final analysis between August 2017 and September 2017 in Beijing Chest Hospital. The overall positive rate of Xpert among sputum samples was 45.9% (256/558), which was significantly higher than that of liquid culture (33.4%, 184/558; < 0.01). The percentage of culture negative result in salivary sputum was significantly higher than that in mucoid sputum [odds ratio (OR): 5.04, 95% confidence interval (95% CI): 2.74-9.28; < 0.01]. In addition, the TB cases having previous treatment history had a higher proportion of culture negative result than new cases (OR: 4.26, 95% CI: 1.61-11.28; = 0.01). In conclusion, the results of this study demonstrate that Xpert outperforms mycobacterial culture in detecting MTB from salivary sputum. In addition, the previously treated patients are more likely to yield negative culture results. Our data will provide important hints to formulate an appropriate diagnostic algorithm for pulmonary tuberculosis based on the appearance of sputum samples.
GeneXpert MTB/RIF (Xpert) 检测法已被推荐用于诊断肺结核，因为其对培养阳性肺结核具有很高的敏感性和特异性。毫无疑问，Xpert 的敏感性不可能比分枝杆菌培养更高，而在我们实验室中，Xpert 在痰样本中的阳性率高于分枝杆菌培养。因此，我们进行了一项前瞻性研究，以确定 Xpert 在临床应用中出现这种意外结果的潜在原因。总体而言，2017 年 8 月至 9 月，我们在北京胸科医院共纳入了 558 名符合纳入标准的患者进行最终分析。Xpert 在痰样本中的总体阳性率为 45.9%（256/558），明显高于液体培养（33.4%，184/558；<0.01）。唾液痰的培养阴性率明显高于黏液痰[比值比（OR）：5.04，95%置信区间（95%CI）：2.74-9.28；<0.01]。此外，有既往治疗史的结核病患者比新发病例的培养阴性率更高（OR：4.26，95%CI：1.61-11.28；=0.01）。总之，本研究结果表明，Xpert 检测唾液痰中的 MTB 优于分枝杆菌培养。此外，既往治疗的患者更有可能产生培养阴性结果。我们的数据将为制定基于痰样本外观的肺结核适当诊断算法提供重要提示。
