Evaluation of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry in Identification of Nontuberculous Mycobacteria

Abstract

Background/Aims: Species-level identification of nontuberculous mycobacteria (NTM) is important in making decisions about the necessity and choice of antimicrobial treatment. The reason is predictable clinical significance and the susceptibility profile of specific NTM species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is recognized as a diagnostic tool for routine identification of bacteria and yeasts in the clinical laboratory based on protein fingerprint analysis. The aim of the study was to evaluate MALDI-TOF MS in the identification of NTM. Methods: A total of 25 NTM isolates from liquid cultures were identified with both polymerase chain reaction (PCR)-based hybridization assay and MALDI-TOF MS at the University Hospital Center Zagreb. Results: PCR-based hybridization assay identified 96% (24/25) and MALDI-TOF MS 80% (20/25) of tested NTM isolates. Five isolates with no reliable MALDI-TOF MS identification belonged to the Mycobacterium avium-intracellulare complex. Seventy percent (14/20) of NTM isolates successfully identified with MALDI-TOF MS had a score higher than 2.0, indicating reliable species identification. Conclusion: MALDI-TOF MS is a promising tool for the identification of NTM. With a further improvement of the protein extraction protocol, especially regarding the M. avium-intracellulare complex, MALDI-TOF MS could be an additional standard method for identification of NTM.

Characterization and Differentiation of Mycobacterium avium subsp. paratuberculosis from Other Mycobacteria Using Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

“…These studies also lacked uniformity in sample preparation. Samples for mass spectrometry included whole cells in matrix solution (Lin et al, 2013), cells directly applied on MALDI plates (Pignone et al, 2006), non-sonicated cell-free supernatants (Hettick et al, 2006), mechanical breaking of heat-inactivated cells followed by protein extractions with formic acid and acetonitrile (El Khechine et al, 2011) or protein extraction from culture supernatants (Marekovic et al, 2016). Cell lysates were used routinely for MALDI-TOF characterization of foodborne pathogens in our laboratory (Mandrell et al, 2005; Fagerquist et al, 2010; Penny et al, 2016).…”

Rapid Diagnosis ofMycobacterium abscessusBacteremia Using Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry

“…Recent studies have shown that M. abscessus and other mycobacterial species can be identified by MALDI-TOF MS [7,8,11,12]. In study which compares MALDI-TOF MS and reverse hybridization-based assay for the identification of NTM, the concordance analysis between the two methods showed agreement in 96.9% [7].…”

“…Recently, the introduction of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides a rapid identification for clinical isolates of NTM. The identification ability of MALDI-TOF MS for NTM has been assessed and improved by several studies in various setting of the composition of database, or sample pretreatment [7,8]. Here, we report a rare case of M. abscessus bacteremia in which blood isolates were identified by MALDI-TOF MS.…”

Persistent Cutaneous Infection Due to Mycobacterium Immunogenum, a Relatively Novel Species

“…6 The MALDI-TOF spectrometry method used to identify M. immunogenum in this case, utilizes protein fingerprint analysis to identify bacteria and yeast. 7 M. immunogenum has been implicated as the causative agent in several reported skin infections (Table 1). These cases were observed after penetrating trauma like tattoo needles, medication injections, and intravenous catheters.…”

“…2,4,8 Similar to other NTM, M. immunogenum is capable of contaminating hospital water and equipment due to its resistance to a variety of DISCUSSION disinfectants, biocides, and its ability to form biofilms. 7 In a one study, M. immunogenum was the second most common NTM isolated from swimming pools. Unlike other NTM species, M. immunogenum was not isolated in spas or whirlpools.…”