Evaluation of the VITEK MS knowledge base version 3.0 for the identification of clinically relevant Mycobacterium species

Abstract

Different Mycobacterium spp. infections may indicate varied treatment regimens in the clinic. Thus, the species-level identification of Mycobacterium spp. is one of the most important tasks for a clinical microbiology laboratory. Although matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid and accurate method for the identification of mycobacteria, this method lacks a comprehensive evaluation of the identification accuracy for clinically collected mycobacteria using VITEK MS Knowledge Base Version 3.0 (Ver 3.0). The objectives of the present study were to evaluate the identification performance of Mycobacterium spp. using Ver 3.0 and a sample processing kit for strain inactivation and protein extraction. Among the 507 Mycobacterium isolates, 46 isolates were M. tuberculosis, and 461 isolates were nontuberculous mycobacteria (NTM) (including 27 species: 17 species were slowly growing mycobacteria (SGM), and 10 species were rapidly growing mycobacteria (RGM)). The VITEK MS V3.0 library was used to correctly identify 476/507 (93.9%) isolates (425 isolates were correctly identified initially, and 51 more isolates were correctly identified on repeat), 23/507 (4.5%) isolates were unidentified, and 8/507 (1.6%) isolates were misidentified. In summary, we showed that Mycobacterium spp. can be adequately identified by Ver 3.0 in combination with the use of a standard sample processing kit.

Nontuberculous Mycobacteria – Clinical and Laboratory Diagnosis: Experiences from a TB Endemic Country

“…In a similar study performed by Luo et al on the evaluation of VITEK R MS version 3.0 for NTM identification, 425/507 (83.8%) isolates were identified the first time, 51/507 (11.24%) additional isolates were identified on repeat, 23/507 (4.53%) isolates remained unidentified and 8/507 (1.6%) isolates were misidentified at species level. Among slowly growing NTM, only 2 out of 56 (3.6%) M. avium and 3 out of 153 (2%) M. intracellulare were unidentified, which was marginally better than the findings in this study [8]. The concordance of 77.5% between VITEK R MS and 16S rRNA sequencing in the identification of slowly growing Mycobacteria is predominantly due to the fact that MALDI-TOF requires moderate growth to be present on the solid media for identification, rather than the scant growth required for sequencing, as demonstrated by other studies as well [37].…”

“…The two MALDI-TOF mass spectrometry (MS) platforms, namely VITEK ® MS (bioMérieux, Marcy-l'Étoile, France) and Bruker Daltonics platform (Bremen, Germany) for NTM identification, have been evaluated to identify NTM from both solid and liquid media. VITEK ® MS is a rapid, cost effective and reliable platform, which has the capability to identify as many as 24 NTM species [ 7 , 8 ]. This technology is designed to provide a protein ‘fingerprint’ based on the desorbed ions from cell surfaces by measuring their mass-to-charge ratio.…”

Nontuberculous mycobacteria in China: incidence and antimicrobial resistance spectrum from a nationwide survey

“…The development of several extraction methods enhances the number of bacterial proteins available for MALDI-TOF MS identification. With the increasing amount of mycobacteria data available in commercial databases, MALDI-TOF MS technology has been implemented for NTM identification in many laboratories [ 8 , 19 ]. Several studies have demonstrated that this method can achieve more than 95% agreement with results from DNA sequencing of variable genomic regions (including the 16S rRNA, hsp65 , rpoB , and ITS genes) [ 5 , 20 ].…”

Nontuberculous Mycobacteria in China-incidence and Antimicrobial Resistance Spectrum From a Nationwide Survey

“…The laboratory diagnosis methods used for identi cation of mycobacterial species have evolved over the decades [18]. With the development of several extraction methods that enhance the amount of bacterial proteins available for MALDI-TOF MS identi cation, and the increasing amount of mycobacteria data available in commercial databases, MALDI-TOF MS technology has been implemented for NTM identi cation in many laboratories [8,19]. Several studies have demonstrated that this method can achieve more than 95% agreement with results from DNA sequencing of variable genomic regions (including the 16S rRNA, hsp65, rpoB, and ITS genes) [5,20].…”