Comparison of MycoPrep and the new MYCO-TB kit: rapid and efficient digestion and decontamination of respiratory specimens for the detection of Mycobacteria

Abstract

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.

Keywords: MYCO-TB; MycoPrep; Mycobacteria; Respiratory samples; decontamination; liquid culture; solid culture.