Biology subjects

Baron, S. A.

Publications and source records attributed to Baron, S. A..

2 recordsLinked to original sources

bioRxiv2021

Speciation of the Mycobacterium tuberculosis complex using mass spectrometry: a proof-of-concept.

Mycobacteria that form the Mycobacterium tuberculosis complex are responsible for deadly tuberculosis in animals and patients. Identification of these pathogens at the species level is of primary importance for treatment and source tracing, and currently relies on DNA analysis, including whole genome sequencing (WGS), which takes a whole day. In this study, we report on the unprecedented identification of the M. tuberculosis complex species using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS), with WGS as the comparative gold standard. In a first step, an optimised peptide extraction applied to 24 isolates otherwise identified in three of the 11 M. tuberculosis complex species by WGS, yielded 94 MALDI-TOF spectra which clustered according to WGS identification. In a second step, 70/74 (95%) other isolates were correctly identified at the species level by this clustering method. This study is the first to report a MALDI-TOF-MS method of identification of M. tuberculosis complex mycobacteria at the species level and is easily implantable in clinical microbiology laboratories.

microbiology↗

bioRxiv2019

Massive analysis of 64’628 bacterial genomes to decipher a water reservoir and origin of mobile colistin resistance (mcr) gene variants: is there another role for this family of enzymes?

Since 2015, new worrying colistin resistance mechanism, mediated by mcr-1 gene has been reported worldwide along with eight newly described variants (mcr-2 to mcr-9) but their source(s) and reservoir(s) remain largely unexplored. Here, we conducted a massive bioinformatic analysis of 64628 downloaded bacterial genomes to investigate the reservoir and origin of these mcr variants. We identified a total of 6651 significant positive hits (aa sequence coverage > 90 % and similarity >50%) with the nine MCR variants from these genomes that include 39 bacterial genera and more than 1050 species. Although these variants could be identified in bacteria from human and animal sources, we found plenty MCR variants in unsuspected bacteria from environmental origin, especially from water sources. The ubiquitous presence of mcr variants in bacteria from water likely suggests another role in the biosphere of these enzymes as an unknown defense system against natural antimicrobial peptides and/or bacteriophage predation.

genomics↗