Naslov
Evaluation of MALDI Biotyper Mycobacteria Library v6.0 for identification of nontuberculous mycobacteria in routine clinical microbiology – experience from the University Hospital Centre Zagreb

Autori
Markanović, Manda ; Herljević, Zoran ; Bošnjak, Zrinka ; Budimir, Ana ; Janković Makek, Mateja ; Mareković, Ivana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, pp prezentacija, stručni

Skup
32th European Congress of Clinical Microbiology

Mjesto i datum
Lisabon, Portugal, 23.04.2022. - 26.04.2022

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
nontuberculous mycobacteria, identification, MALDI-TOF MS

Sažetak
Background Current clinical guidelines recommend that all nontuberculous mycobacteria (NTM) isolates from respiratory samples should be identified to at least species level using validated molecular or mass spectrometry techniques. In recent years matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is constantly improving in this field by optimizing protein extraction protocols and by databases increasing the number of species that can be reliably identified. The aim of this study was to evaluate MALDI Biotyper Mycobacteria Library v6.0 (Bruker Daltonics GmbH, Bremen, Germany), predominantly used in the laboratories with MALDI Biotyper at the moment, for identification of routine clinical NTM isolates. Materials Eighty NTM isolates identified previously with PCR-reverse hybridization (Hain Lifescience GmbH, Nehren, Germany) were collected at the University Hospital Centre Zagreb, Zagreb, Croatia between January 2014 and November 2021. The isolates were grown on solid medium and identified after protein extraction using MALDI Biotyper Mycobacteria Library v6.0 with each isolate applied to eight spots and mean scores used in analysis. According to manufacturer, scores of ≥1.80 and 1.60 to 1.79 represented high confidence and low confidence identification, respectively. A score of <1.60 was considered unreliable. Results Seventy-six (95.0% ; 76/80) NTM isolates obtained correct MALDI-TOF MS identification. Only 3.95% (3/76) were identified with a mean score below 1.8 and none with score below 1.6. Three isolates with mean score below 1.8 were slow growing mycobacteria (Table 1). In comparison to PCR-reverse hybridization, discordant results were found in four (5.0% ; 4/80) NTM isolates. Discordant results were result of inability of PCR-reverse hybridization to distinguish between M. scrofulaceum and M. parascrofulaceum as well as to distinguish phylogenetically close species belonging to the M. fortuitum complex (M. fortuitum and M. peregrinum) and M. avium complex (M. intracellulare and M. marseillense) (Table 2, Figure 1). Conclusions We demonstrated a high rate of high confidence NTM identifications using Mycobacterium Library v6.0. on routine clinical isolates. Discordant results were consequence of PCR-reverse hybridization being limited to certain number of species and its inability to distinguish between closely related species. Our results underline importance of introducing MALDI-TOF MS and its constantly updated database in rapid and accurate identification of NTM isolates.

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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