Xpert MTB/RIF在呼吸道标本检出极低值并利福平耐药时的诊断可靠性分析

Diagnostic reliability of Xpert MTB/RIF with rifampicin resistance detected at very low bacterial level:a retrospective analysis

目的评估Xpert MTB/RIF在呼吸道标本检出极低值并利福平耐药时的诊断可靠性,为结核病诊断提供参考。方法回顾深圳市第三人民医院使用Xpert MTB/RIF检测的4476份呼吸道标本结果,其中95份标本的检测结果为"检测到结核分枝杆菌(MTB)极低值;利福平耐药检出",比较这95份标本的Xpert MTB/RIF检测结果与基于液体培养的表型药物敏感性测试(DST)及第2次Xpert MTB/RIF检测结果的一致性,同时分析9例结果不一致患者的治疗效果。结果共送检93份呼吸道标本进行液体培养,其中65份报告MTB阳性,28份MTB阴性。在59份基于液体培养结果的DST中,有51份显示出对利福平耐药,8份显示出对利福平敏感,Xpert MTB/RIF和DST检测的一致性为86%(51/59)。28份标本进行第2次Xpert MTB/RIF检测,结果20份呈MTB阳性,2次Xpert MTB/RIF检测的一致性为80%(16/20)。9例结果不一致的患者成功治愈,使用一线药物治疗8例,二线药物治疗1例。结论 Xpert MTB/RIF即使在极低的细菌载量下也显示出检测利福平耐药的可靠性,可作为诊断利福平耐药的重要检测手段,而进行第2次Xpert检测,能使诊断更加精准。

Objective To evaluate the reliability of Xpert MTB/RIF assay with rifampicin resistance detected at very low bacterial level on sputum and bronchoalveolar lavage fluid specimens and provide reference for tuberculosis diagnosis.Methods A total of 4476 respiratory specimens detected by Xpert MTB/RIF assay were reviewed.Among them,95 specimens yielded test results of "MTB detected,very low;Rifampicin resistance detected".A retrospective analysis of these 95 results was performed to compared the consistency of rifampicin resistance detected by Xpert MTB/RIF and culture-based DST and repeated Xpert MTB/RIF.And the treatment outcome of 9 patients with discordant results was analyzed.Results There were 93 respiratory specimens sent for liquid culture and 65 reported MTB positive and 28 MTB negative.In the 59 culture-based DST,51 showed rifampicin resistant and 8 rifampicin susceptible.The consistency of Xpert and DST was 86%(51/59);28 specimens were sent for a repeated Xpert and 20 turned out MTB positive,of which 16 were found to be rifampicin resistant at the same probe as the first Xpert.4 showed no rifampicin resistance detection.The consistency of two Xpert tests were 80%(16/20);9 patients with discrepant results were successfully cured,8 with first line medicine and 1 with second line regimen.Conclusion Xpert MTB/RIF shows reliability in detecting rifampicin resistance even ata very low bacterial load,but a repeated Xpert or culture-based DST is recommended for more precise diagnosis.