Table 1. Rates of correct identification of different mycobacterial species using the conventional Microchip MTB method compared to direct identification from positive MGIT broths using the MALDI-TOF MS Vitek MS system with a IVD database (v3.0) prepared without any washing step (Direct) and washed once with 0.1% SDS (SDS) protocol (N = 83).
| Species | No. of samples | No. of samples identified: | ||||
|---|---|---|---|---|---|---|
| First | Repeat | |||||
| Microchip MTB n (%) |
Direct n (%) |
SDS n (%) |
Direct n (%) |
SDS n (%) |
||
| MAC* | 40 | 39 (97.5) | 30 (75.0) | 32 (80.0) | 37 (92.5) | 40 (100.0) |
| M. abscessus | 16 | 16(100.0) | 16 (100.0) | 16 (100.0) | 16 (100.0) | 16 (100.0) |
| M. kansasii | 9 | 9 (100.0) | 8 (88.9) | 8 (88.9) | 9 (100.0) | 9 (100.0) |
| M. fortuitum | 9 | 9 (100.0) | 9 (100.0) | 9(100.0) | 9 (100.0) | 9 (100.0) |
| M. chelonae | 2 | 2 (100.0) | 2 (100.0) | 2 (100.0) | 2 (100.0) | 2 (100.0) |
| M. szulgai | 1 | 1 (100.0) | 1 (100.0) | 1 (100.0) | 1 (100.0) | 1 (100.0) |
| M. gordonae | 3 | 3 (100.0) | 3 (100.0) | 3 (100.0) | 3 (100.0) | 3 (100.0) |
| M. cosmeticum$ | 1 | 0 | 1 (100.0) | 1 (100.0) | 1 (100.0) | 1 (100.0) |
| M. simiae | 1 | 1 (100.0) | 1 (100.0) | 1 (100.0) | 1 (100.0) | 1 (100.0) |
| M. mageritense | 1 | 0 | 1 (100.0) | 1 (100.0) | 1 (100.0) | 1 (100.0) |
| Total | 83 | 80 (97.6) | 72 (86.7) | 74 (89.2) | 80 (96.4) | 81 (100*) |
*MAC: M. avium-intracellulare complex
$Identified as M. neoneunm by Microchip MTB; M. cosmeticum by MS and PRA.