AUTHOR=Epperson L. Elaine , Timke Markus , Hasan Nabeeh A. , Godo Paul , Durbin David , Helstrom Niels K. , Shi Gongyi , Kostrzewa Markus , Strong Michael , Salfinger Max 

TITLE=Evaluation of a Novel MALDI Biotyper Algorithm to Distinguish Mycobacterium intracellulare From Mycobacterium chimaera

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.03140

DOI=10.3389/fmicb.2018.03140

ISSN=1664-302X

ABSTRACT=<p>Accurate and timely mycobacterial species identification is imperative for successful diagnosis, treatment, and management of disease caused by nontuberculous mycobacteria (NTM). The current most widely utilized method for NTM species identification is Sanger sequencing of one or more genomic loci, followed by BLAST sequence analysis. MALDI-TOF MS offers a less expensive and increasingly accurate alternative to sequencing, but the commercially available assays used in clinical mycobacteriology cannot differentiate between <italic>Mycobacterium intracellulare</italic> and <italic>Mycobacterium chimaera</italic>, two closely related potentially pathogenic species of NTM that are members of the <italic>Mycobacterium avium</italic> complex (MAC). Because this differentiation of MAC species is challenging in a diagnostic setting, Bruker has developed an improved spectral interpretation algorithm to differentiate <italic>M. chimaera</italic> and <italic>M. intracellulare</italic> based on differential spectral peak signatures. Here, we utilize a set of 185 MAC isolates that have been characterized using <italic>rpoB</italic> locus sequencing followed by whole genome sequencing in some cases, to test the accuracy of the Bruker subtyper software to identify <italic>M. chimaera</italic> (<italic>n</italic> = 49) and <italic>M. intracellulare</italic> (<italic>n</italic> = 55). 100% of the <italic>M. intracellulare</italic> and 82% of the <italic>M. chimaera</italic> isolates were accurately identified using the MALDI Biotyper algorithm. This subtyper module is available with the MALDI Biotyper Compass software and offers a promising mechanism for rapid and inexpensive species determination for <italic>M. chimaera</italic> and <italic>M. intracellulare</italic>.</p>