GeneXpert MTB/RIF Ultra在结核病特殊标本检测中的应用价值

The application value of GeneXpert MTB/RIF Ultra in the detection of special specimens of tuberculosis

目的比较全自动荧光定量PCR系统超强版本(GeneXpert MTB/RIF Ultra,GeneXpert Ultra,GeneXpert)、全自动荧光定量PCR系统(GeneXpert MTB/RIF,Xpert,GeneXpert)、DNA实时荧光定量核酸检测(FQ-PCR)、结核分枝杆菌RNA实时荧光恒温扩增(SAT-RNA)、DNA实时荧光恒温扩增检测(恒温扩增法)及传统BACTEC MGIT 960液体培养(培养法)对结核病特殊标本的诊断效能,为临床诊疗提供依据。方法收集2021年1—9月西安市胸科医院特殊标本共170例(包括胸腹水标本47例,24 h尿沉渣标本34例,组织标本49例,脓液标本40例),分别采用GeneXpert Ultra、Xpert、FQ-PCR、SAT-RNA、恒温扩增法及传统培养法进行检测,以临床诊断为标准,对比其灵敏度、特异度、阳性预测值、阴性预测值、符合率及Kappa值。结果GeneXpert Ultra、Xpert、FQ-PCR、SAT-RNA、恒温扩增法及传统培养法的灵敏度分别为65.18%(73/112)、49.11%(55/112)、37.50%(42/112)、19.64%(22/112)、8.04%(9/112)和22.32%(25/112),GeneXpert Ultra的灵敏度均高于其他5种方法,差异具有统计学意义(χ^(2)=66.25,42.10,28.89,13.09,4.92,15.18,P<0.05)。GeneXpert Ultra检测显示,5.48%(4/73)结核分枝杆菌为微量负荷,79.45%(58/73)为极低负荷,10.96%(8/73)为低负荷,2.74%(2/73)为中负荷,1.36%(1/73)为高负荷。在4份微量负荷标本中,Xpert检测均为阴性。73份GeneXpert Ultra阳性报告中,63份利福平敏感,6份利福平耐药,4份利福平耐药性不明确;55份Xpert阳性报告中45份利福平敏感,2份利福平耐药,8份利福平耐药性不明确。结论GeneXpert Ultra具有较高的灵敏度、特异度及耐药检出率,对结核病特殊标本病原学诊断的优势更为明显,在载菌量较少的标本中可作为首选方法之一。

Objective To compare the diagnostic efficacy of the upgraded version of the GeneXpert automated fluorescent quantitative PCR system(GeneXpert MTB/RIF Ultra,GeneXpert Ultra)and the original version of the GeneXpert system(GeneXpert MTB/RIF,Xpert),real-time fluorescent quantitative nucleic acid detection(FQ-PCR),real-time fluorescent thermostatic amplification of Mycobacterium tuberculosis RNA(SAT-RNA),real-time fluorescent thermostatic amplification detection of DNA(thermostatic amplification method)and traditional BACTEC MGIT 960 liquid culture(culture method)for special specimens of tuberculosis,in order to analyze its application value in clinical detection.Methods Using prospective research methods,a total of 170 special specimens(including 47 pleural and ascites effusion samples,and 3424-hour urinary sediment specimens,49 tissue specimens and 40 fester specimens)were collected i'an Chest Hospital from January to September 2021.GeneXpert Ultra,Xpert,FQ-PCR,SAT-RNA,isothermal amplification,and traditional culture were used for detection.Clinical diagnosis was used as the standard,and sensitivity,specificity,positive predictive value,negative predictive value,coincidence rate,and Kappa value were compared among the methods.Results The sensitivities of GeneXpert Ultra,Xpert,FQ-PCR,SAT-RNA,isothermal amplification,and traditional culture were 65.18%(73/112),49.11%(55/112),37.50%(42/112),19.64%(22/112),8.04%(9/112),and 22.32%(25/112),respectively.The sensitivity of GeneXpert Ultra was higher than that of the other five methods,and the differences were statistically significant(χ^(2)=66.25,42.10,28.89,13.09,4.92,15.18,all P<0.05).GeneXpert Ultra result analysis showed that:5.48%(4/73)cases had trace,that is,trace Mycobacterium tuberculosis load,79.45%(58/73)cases were extremely low,10.96%(8/73)cases were low,2.74%(2/73)were medium,,and 1.36%(1/73)were high load.In 4 trace samples,the Xpert detection was negative for all.Of the 73 GeneXpert Ultra positive reports,63 were rifampicin-sensitive,6 were rifampicin-resistant,and 4 were rifampicin-resistant but of unclear resistance.Of the 55 Xpert positive reports,45 were rifampicin-sensitive,2 were rifampicin-resistant,and 8 were rifampicinresistant but of unclear resistance..Conclusions The new generation of GeneXpert MTB/RIF Ultra has high sensitivity,specificity and drug resistance detection rate,and its advantage is even more apparent in the pathogenic diagnosis of special specimens of tuberculosis.It can be used as one of the preferred methods in samples with low bacterial load.