【摘要】 目的探讨使用BACTECTM MGIT960进行分枝杆菌培养时,仪器报告结果为阴性的MGIT960培养管中颗粒的性质及成因。方法收集北京市结核病胸部肿瘤研究所2010年1月至2010年12月进行分枝杆菌培养的标本中31份仪器报告阴性但有颗粒形成的培养管,分别对颗粒性物质进行抗酸染色、罗氏培养和BACTECTMMGIT960传代培养。对培养阳性的标本进行菌种鉴定、药敏试验。选择8株培养阳性的标本进行低细菌载量接种试验来分析颗粒形成的原因,包括2株结核分枝杆菌复合群,3株蟾蜍分枝杆菌和3株胞内分枝杆菌,每株将1个麦氏浓度的菌悬液用生理盐水连续稀释至10-5、10-6、10-7、10-8倍,各接种到2支培养管。结果31份仪器报告阴性但有颗粒形成的培养管,有29份经再次传代培养后获得阳性培养结果,其中24份(24/29)用颗粒直接涂片后进行显微镜抗酸杆菌检查结果为阳性。29份培养阳性的菌株包括7株蟾蜍分枝杆菌,4株胞内分枝杆菌和18株结核分枝杆菌复合群。接种量为10-6、10-7、10-8浓度的蟾蜍分枝杆菌培养管中均有颗粒形成,阳性比例分别为4/6、5/6、6/6。结论BACTECTM MGIT960进行结核分枝杆菌培养时,仪器报告阴性的MGIT960培养管中颗粒多为活的分枝杆菌;BACTECTM MGIT960系统颗粒的形成与低细菌载量有关,颗粒形成也有一定的种属特异性,主要集中在蟾蜍分枝杆菌和胞内分枝杆菌。更多还原

【Abstract】 Objective To investigate the properties and the forming reasons of granules in the BACTECTM MGIT960-negative culture from Mycobacterium growth indicator tube(MGIT).Methods The granules were collected from 31 BACTECTM MGIT960-negative culture tubes,and then performed acid-fast bacilli(AFB) examination,BACTECTM MGIT960 culture and Lwenstein-Jensen(LJ) medium culture,respectively.The positive cultures were performed species identification and drug susceptibility tests.M.tuberculosis strain H37Rv(ATCC strain 27294) and 8 clinical isolates acquired from the granules subculture were selected for the inoculation tests.The 8 strains included 2 M.tuberculosis complex(MTC) strains,3 M.xenopi strains and 3 M.intracellulare strains.The isolates were adjusted to the McFarland no.1 turbidity standard,which were diluted to 10-5,10-6,10-7,10-8 suspensions.An aliquot of each preparation was inoculated into the MGIT vials in duplicate.Results Of 31 granules from BACTECTM MGIT960-negative culture tubes,29 were subculture positive by either MGIT 960 or/and LJ medium,in which 24 granules were AFB smear positive,and 18,4 and 7 isolates were identified as MTC,M.intracellulare and M.xenopi,respectively.A limited amount of 8 clinical isolates and H37Rv strain were inoculated,granule formation was observed in the MGIT-negative culture inoculated respectively with 10-6(granule in 4/6 tube),10-7(granule in 5/6 tube),10-8(granule in 6/6 tube) of M.xenopi strains after incubation for 6 weeks.Conclusion The granules in BACTECTM MGIT960-negative culture tubes are more likely to be live mycobacteria.The granule formation in the MGIT960 may be correlated with a low bacterial load in the tested specimens,might also be a species-specific feature of M.xenopi and M.intracellulare.更多还原