Comparative evaluation of the identification of rapidly growing non-tuberculous mycobacteria by mass spectrometry (MALDI-TOF MS), GenoType Mycobacterium CM/AS assay and partial sequencing of the rpoβ gene with phylogenetic analysis as a reference method

Evaluation and clinical impact of MALDI Biotyper Mycobacteria Library v6.0 for identification of nontuberculous mycobacteria by MALDI-TOF mass spectrometry

Major challenges in the identification of non-tuberculous mycobacteria (NTM) by MALDI-TOF MS include protein extraction protocol and updating of the NTM database. The aim of this study was to evaluate MALDI Biotyper Mycobacteria Library v6.0 (Bruker Daltonics GmbH, Bremen, Germany) for identification of clinical NTM isolates and its impact on clinical management. NTM isolates cultivated from clinical samples in 101 patients were identified simultaneously by PCR-reverse hybridization (Hain Lifescience GmbH, Nehren, Germany) as a routinely used reference molecular method and using MALDI Biotyper Microflex LT/SH after protein extraction. Each isolate was applied to eight spots, and mean scores were used in analysis. MALDI-TOF MS obtained correct identification to the species level for 95 (94.06%) NTM isolates. The majority of correctly identified isolates (92/95; 96.84%) were identified with high-confidence score of ≥1.80 and only 3.16% (3/95) with a score of <1.80. Mean value ± SD of RGM NTM isolates (2.127 ± 0.172) was statistically significant higher in comparison to SGM NTM isolates (2.027 ± 0.142) with a p value of 0.007. In comparison to PCR-reverse hybridization, discordant identification results by MALDI-TOF MS were found in six (6/101; 5.94%) NTM isolates for which clinical data were analyzed. We demonstrated a high confidence NTM identifications using Mycobacterium Library v 6.0 on routine clinical isolates. This is the first study that analyzed MALDI-TOF MS identification results of NTM isolates in the context of clinical data, and it showed that MALDI-TOF MS with its updated databases could help clarify the epidemiology, clinical characteristics, and course of infections caused by less frequent NTM species.

A rapid proteomic system (MALDI-TOF) for nontuberculous-mycobacteria identification

Proteomic techniques relaying upon mass spectrometry (MALDI_TOF) applied to nontuberculous mycobacteria (NTM) identification, constitute a difficult goal. Cell wall structure features complicates the protein extraction procedure. A total of 106 isolates belonging to a variety of MNTs species isolated from clinical samples taken at the Complejo Asistencial Universitario de León for a two years period (2019-20) were identified following a simplified method (MALDI-TOF Biotyper Bruker®) developped in our laboratory. The resultant identification was compared to a parallel one ruled on the Centro de Referencia de Majadahonda. A total of 22different MNTs species were tested, obtaining an agreement of 92,45%. Only 8 minor discrepancies between species belonging to same taxonomic group of MNTs were detected. The score obtained in the 67.92% of the cases was higher than 1.8. A time-saving of 24min compared to the manufacturer's proceeding was achieved.

A rapid proteomic system (MALDI-TOF) for nontuberculous-mycobacteria identification

Proteomic techniques relaying upon mass spectrometry (MALDI_TOF) applied to nontuberculous mycobacteria (NTM) identification, constitute a difficult goal. Cell wall structure features complicates the protein extraction procedure. A total of 106 isolates belonging to a variety of MNTs species isolated from clinical samples taken at the Complejo Asistencial Universitario de León for a two years period (2019-20) were identified following a simplified method (MALDI-TOF Biotyper Bruker®) developped in our laboratory. The resultant identification was compared to a parallel one ruled on the Centro de Referencia de Majadahonda. A total of 22 different MNTs species were tested, obtaining an agreement of 91,5%. Only 9 minor discrepancies between species belonging to the same taxonomic group of MNTs were detected. The score obtained in the 67.92% of the cases was higher than 1.8. A time-saving of 24 minutes compared to the manufacturer's proceeding was achieved.

Leprosy in the twenty-first century: a microbiological, clinical, and epidemiological study in northwestern Spain

Leprosy, or Hansen's disease, is a chronic granulomatous disease caused by Mycobacterium leprae and the recently discovered Mycobacterium lepromatosis. In Spain and other countries, where leprosy has been eliminated, an increasing number of imported cases have been documented, especially from South Africa and South America. The diagnosis of leprosy is mainly clinical, based on the signs established by the World Health Organization (WHO), although laboratory tools can be useful for diagnostic confirmation. The treatment is based on the administration of multi-drug therapy, and involves the multidisciplinary work of experts in ophthalmology, orthopedics, and physiotherapy. We studied the confirmed cases by microbiological and /or histopathological diagnosis in the health area of Santiago de Compostela (456,874 inhabitants in Galicia, in the Northwest of Spain), analyzing their clinical, microbiological, and epidemiological characteristics (2006-2015). In our study, we describe five cases of leprosy, four of them imported and one that, in the absence of more data, is native. Although we have only documented five cases during the 10 years of the study, our experience highlights the importance of considering the country of origin, travel history, and contacts in patients or staff working with leprosy patients. Despite the decrease of leprosy in our environment, it is important to enhance suspicion of the disease among health personnel, especially in those patients from countries where leprosy is endemic and those in close contact with the diagnosed patients.

The expanding use of matrix-assisted laser desorption/ionization-time of flight mass spectroscopy in the diagnosis of patients with mycotic diseases

INTRODUCTION

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a powerful new tool to identify human fungal pathogens and has radically altered the diagnostic mycology workflow at many medical centers around the world. Areas covered: While most experience is with the identification of yeasts, including species of Candida and Cryptococcus, there is ongoing work investigating the role of MALDI-TOF MS to detect molds, including species of Aspergillus, Fusarium, Scedosporium, and Mucormyctes as well as thermally dimorphic fungi. Expert commentary: In this paper, we review the current knowledge about this important new platform and examine how its expanding use may impact molecular diagnostics and patient care in the years ahead.

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

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 Mycobacterium intracellulare and Mycobacterium chimaera, two closely related potentially pathogenic species of NTM that are members of the Mycobacterium avium complex (MAC). Because this differentiation of MAC species is challenging in a diagnostic setting, Bruker has developed an improved spectral interpretation algorithm to differentiate M. chimaera and M. intracellulare based on differential spectral peak signatures. Here, we utilize a set of 185 MAC isolates that have been characterized using rpoB locus sequencing followed by whole genome sequencing in some cases, to test the accuracy of the Bruker subtyper software to identify M. chimaera (n = 49) and M. intracellulare (n = 55). 100% of the M. intracellulare and 82% of the M. chimaera 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 M. chimaera and M. intracellulare.