Evaluation of the Vitek MS v3.0 Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Mycobacterium and Nocardia Species

Barbara A. Body; Melodie A. Beard; E. Susan Slechta; Kimberly E. Hanson; Adam P. Barker; N. Esther Babady; Tracy McMillen; Yi-Wei Tang; Barbara A. Brown-Elliott; Elena Iakhiaeva; Ravikiran Vasireddy; Sruthi Vasireddy; Terry Smith; Richard J. Wallace; S. Turner; L. Curtis; Susan Butler-Wu; Jenna Rychert

doi:10.1128/JCM.00237-18

DOI: 10.1128/JCM.00237-18

ABSTRACT

This multicenter study was designed to assess the accuracy and reproducibility of the Vitek MS v3.0 matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry system for identification of Mycobacterium and Nocardia species compared to DNA sequencing. A total of 963 clinical isolates representing 51 taxa were evaluated. In all, 663 isolates were correctly identified to the species level (69%), with another 231 (24%) correctly identified to the complex or group level. Fifty-five isolates (6%) could not be identified despite repeat testing. All of the tuberculous mycobacteria (45/45; 100%) and most of the nontuberculous mycobacteria (569/606; 94%) were correctly identified at least to the group or complex level. However, not all species or subspecies within the M. tuberculosis, M. abscessus, and M. avium complexes and within the M. fortuitum and M. mucogenicum groups could be differentiated. Among the 312 Nocardia isolates tested, 236 (76%) were correctly identified to the species level, with an additional 44 (14%) correctly identified to the complex level. Species within the N. nova and N. transvalensis complexes could not always be differentiated. Eleven percent of the isolates (103/963) underwent repeat testing in order to get a final result. Identification of a representative set of Mycobacterium and Nocardia species was highly reproducible, with 297 of 300 (99%) replicates correctly identified using multiple kit lots, instruments, analysts, and sites. These findings demonstrate that the system is robust and has utility for the routine identification of mycobacteria and Nocardia in clinical practice.

FOOTNOTES

Received 9 February 2018.
Returned for modification 8 March 2018.
Accepted 8 April 2018.
Accepted manuscript posted online 11 April 2018.

Address correspondence to Jenna Rychert, Jennifer.Rychert{at}aruplab.com.
↵* Present address: Barbara A. Body (retired), Charlottesville, Virginia, USA; Susan Butler-Wu, Department of Pathology & Laboratory Medicine, University of Southern California, Los Angeles, Los Angeles, California, USA.
Citation Body BA, Beard MA, Slechta ES, Hanson KE, Barker AP, Babady NE, McMillen T, Tang Y-W, Brown-Elliott BA, Iakhiaeva E, Vasireddy R, Vasireddy S, Smith T, Wallace RJ, Jr, Turner S, Curtis L, Butler-Wu S, Rychert J. 2018. Evaluation of the Vitek MS v3.0 matrix-assisted laser desorption ionization–time of flight mass spectrometry system for identification of Mycobacterium and Nocardia species. J Clin Microbiol 56:e00237-18. https://doi.org/10.1128/JCM.00237-18.