Bisognin Francesco, Lombardi Giulia, Lombardo Donatella, Re Maria Carla, Dal Monte Paola
Department of Experimental,Diagnostic and Specialty Medicine -Unit of Microbiology, Alma Mater Studiorum University of Bologna - S.Orsola-Malpighi University Hospital, v. Giuseppe Massarenti 9,40138.
New Microbiol. 2020 Jan;43(1):13-16. Epub 2019 Dec 13.
The long incubation time required for Mycobacteria detection may allow cultures to become overgrown by contaminating organisms. Therefore, samples need to be decontaminated before solid and liquid culture. MYCO-TB is a ready-to-use digestion and decontamination kit with single-sample formulation developed by Copan. Sample processing time (3 minutes) is shorter than that of other commercial kits. The aim of this study was to compare the performance of MYCO-TB with MycoPrep, both based on N-acetyl-Lcysteine and sodium hydroxide solution, in terms of culture contamination and Mycobacterial detection by culture. We tested 162 respiratory samples: the overall proportions of contamination of both liquid and solid media were 1.8% for MYCO-TB and 1.8% for MycoPrep. Mycobacterial growth was detected without significant differences in times to positivity (TTP) in liquid culture: 10.5 days for MYCO-TB and 11.1 days for MycoPrep. Samples decontaminated with MYCO-TB were suitable for molecular assays such as Xpert MTB/RIF Ultra and GenoType CMdirect. Extending decontamination times (up to 10 minutes) with MYCO-TB of 20 Mycobacteria-positive specimens did not produce any difference in TTP in liquid culture or in Ultra IS1081/IS6110 probe Ct values. In conclusion, the MYCO-TB kit proved to be effective for the rapid digestion and decontamination of respiratory materials for the detection of Mycobacteria, making it possible to reduce the manual skills required and lower the risk of contamination. Longer decontamination time could be used for samples with a high level of contamination, such as those from cystic fibrosis patients.
检测分枝杆菌所需的较长孵育时间可能会使培养物被污染菌过度生长。因此，在进行固体和液体培养之前，样本需要进行净化处理。MYCO-TB是由科潘公司开发的即用型消化和净化试剂盒，具有单样本配方。样本处理时间（3分钟）比其他商业试剂盒短。本研究的目的是比较基于N-乙酰-L-半胱氨酸和氢氧化钠溶液的MYCO-TB与MycoPrep在培养污染和通过培养检测分枝杆菌方面的性能。我们检测了162份呼吸道样本：MYCO-TB和MycoPrep在液体和固体培养基中的总体污染比例均为1.8%。在液体培养中检测到分枝杆菌生长，阳性时间（TTP）无显著差异：MYCO-TB为10.5天，MycoPrep为11.1天。用MYCO-TB净化的样本适用于分子检测，如Xpert MTB/RIF Ultra和GenoType CMdirect。对20份分枝杆菌阳性标本延长MYCO-TB的净化时间（长达10分钟），在液体培养的TTP或Ultra IS1081/IS6110探针Ct值方面没有产生任何差异。总之，MYCO-TB试剂盒被证明对呼吸道材料进行快速消化和净化以检测分枝杆菌是有效的，从而可以减少所需的手工操作技能并降低污染风险。对于污染程度高的样本，如囊性纤维化患者的样本，可以使用更长的净化时间。
