Implementation of MALDI-TOF MS technology for the identification of clinical isolates of Mycobacterium spp. in mycobacterial diagnosis

A total of 243 clinical isolates of the Mycobacterium genus were studied, 143 and 100 using two protocols (Protocol v2 and Protocol v3, respectively) provided by the manufacturer. The overall correlation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with the standard identification methods was 63.8 %. The rate of misidentification was 3.2 %, mainly affecting very close species. In Protocol v2, the correlation was 57.3 %, being greater in solid than in liquid media (71.7 % vs. 44.7 %, p < 0.05). Albeit not significant, a trend to a greater correlation for M. tuberculosis complex compared to non-tuberculous mycobacteria (NTM) (63.6 % vs. 55.5 %) was observed. In Protocol v3, the correlation was 73 %, with no significant differences between solid and liquid media (70.8 % vs. 75 %). In conclusion, MALDI-TOF MS may play a role in identifying mycobacterial species isolated from clinical samples, being faster than sequencing and hybridization-based techniques.