摘要
目的探讨Xpert MTB/RIF检测痰标本中结核分枝杆菌(MTB)的最佳实验条件并进行方法学评价。方法应用Xpert MTB/RIF检测MBT标准株H37Rv、H37Ra和牛分枝杆菌及20种常见非结核分枝杆菌(NTM)、18种非分枝杆菌病原体和临床分离株,分析Xpert MTB/RIF的敏感性、特异性和重复性,比较不同前处理方法对实验结果的影响,针对仪器出现的报警、错误及无效结果进行相应的处置和总结。结果 MTB标准菌株H37Rv、H37Ra和牛分枝杆菌Xpert MTB/RIF检测阳性,敏感度为1×102 CFU/ml(在痰标本中的检测极限为106 CFU/ml);20种常见NTM和18种非分枝杆菌病原体检测阴性;标本中含有1%浓度的红细胞、白细胞、血清未对103/ml的H37Rv产生干扰作用;重复试验表明本法批间、批内变异系数均小于15%。100株MTB(其中50株Hain线性探针试验确认存在rpoB基因突变)和20株NTM临床分离株加入阴性临床痰标本制备成为含菌浓度为2×102条/ml的模拟痰标本经Xpert MTB/RIF检测均相符。在SR处理液加入半胱氨酸的改良直接法前处理痰液Xpert MTB/RIF检测出现"错误+无效"的比例显著低于沉淀处理法和直接法前处理的痰标本(χ2值分别为4.19和6.74,P<0.01)。结论 Xpert MTB/RIF灵敏、特异、快速、简便,可用于MTB和利福平耐药MTB的快速检测,但仍存在错误和无效检测而影响实验结果,应采取有效措施予以避免。
Objective To conduct a methodological study to determine the optimal experimental conditions for use of Xpert MTB/RIF to detect Mycobacterium tuberculosis in sputum specimens. Methods The H37Rv and H37Ra refer- ence strains of M. tuberculosis, strains of M. boris, 20 types of common non-tuberculous mycobacteria （NTM）, 18 types of non-mycobacterial pathogens, and clinical isolates were used along with negative sputum specimens. The sensitivity, specificity and repeatability of Xpert MTB/RIF were analyzed. An interference test was conducted by adding 1% red blood cells, white blood cells, and serum to sputum specimens containing bacteria. The effects of different pre-treatments on the experimental results were compared, and alarms, errors, and invalid results yielded by equipment were dealt with and summarized accordingly. Results Xpert MTB/RIF detected the H37Rv and H37Ra reference strains of M. tuber culosis and strains of M. boris with a sensitivity of 1 ×10^2 CFU/ml （the detection limit for sputum specimens was 106 CFU/ml）. Xpert MTB/RIF did not detect 20 types of common NTM or 18 types of non-mycobaeterial pathogens. Speci- mens containing 1% red blood cells, white blood cells, or serum did not interfere with H37Rv production of 10^3/ml. A re-test indicated that the intra-bateh and inter-batch coefficients of variation were both less than 15%. One hundred strains of M. tuberculosis （50 of those strains had a mutation in the rpoB gene that was verified with a line probe assay） and 20 NTM clinical isolates were added to negative sputum samples to prepare simulated sputum specimens with a con- centration of 2 ×10^2/ml, and Xpert MTB/RIF results accorded with that value. Three different pretreatments were compared. When modified direct pre-treatment of sputum was performed and cysteine was added to sample reagent, Xpert MTB/RIF yielded a markedly lower ratio＂errors＋ invalid results＂ than when precipitation treatment or direct pre-treat-ment of specimens was performed （X2 values were 4. 19 and 6.74, respectively, P〈0.01）. Conclusion Xpert MTB/ RIF is sensitive, specific, rapid, and simple, and this technique can he used to rapidly detect M. tuberculosis and rifampi- cin resistant M. tuberculosis. However, this technique does yield errors and invalid results that affect the experimental results, so effective countermeasures should be taken to avoid those problems.
作者
纪丽微
林健雄
彭东东
李耿聪
蓝邦阳
JI Li-wei LIN Jian-xiong PENG Dong-dong LI Gen-cong LAN Bang-yang(Guangdong Shantou Tu- berculosis Control Institute, City of Shantou , Shantou 515041, Guangdong, China)
出处
《中国病原生物学杂志》
CSCD
北大核心
2017年第6期549-552,共4页
Journal of Pathogen Biology
基金
广东省汕头市科技重点攻关课题(No.2014069)
