Abstract
Resistance to polymyxins in most Gram-negative bacteria arises from chemical modifications to the lipid A portion of their lipopolysaccharide (LPS) mediated by chromosomally encoded mutations or the recently discovered plasmid-encoded mcr genes that have further complicated the landscape of colistin resistance. Currently, minimal inhibitory concentration (MIC) determination by broth microdilution, the gold standard for the detection of polymyxin resistance, is time consuming (24 h) and challenging to perform in clinical and veterinary laboratories. Here we present the use of the MALDIxin to detect colistin resistant Salmonella enterica using the MALDxin test on the routine matrix-assisted laser desorption ionization (MALDI) Biotyper Sirius system.
Highlights
Due to the limited pipeline of new antibiotics the increasing trend in antibiotic resistance is threatening the global health
These MDR bacteria may accumulate in a single strain resistance to the main classes of antimicrobial molecules, making colistin one of the last resort therapies for the treatment of infection caused by MDR Gram-negative bacteria
We report on the application of the optimized MALDIxin, which has been applied to E. coli, K. pneumoniae and Acinetobacter baumannii (Dortet et al, 2018a,b, 2019; Furniss et al, 2019), using routine matrix-assisted laser desorption ionization (MALDI) mass spectrometer and its application into the detection of colistin-resistant S. enterica
Summary
Due to the limited pipeline of new antibiotics the increasing trend in antibiotic resistance is threatening the global health. In Gram-negative bacteria, acquired resistance to colistin results mostly from modifications of the drug target, i.e., the lipopolysaccharide (LPS) These modifications correspond to addition(s) of cationic groups such as 4-amino-L-arabinose (L-Ara4N) and/or phosphoethanolamine (pETN) on the lipid A, the anchor of the LPS (Olaitan et al, 2014; Zhang et al, 2019b). These modifications may result from chromosome-encoded mechanisms such as modification (basically mutations) of the two-component systems PmrA/PmrB and PhoP/PhoQ or alteration (mutation, disruption, down-regulation) of the global regulator MgrB. We report on the application of the optimized MALDIxin, which has been applied to E. coli, K. pneumoniae and Acinetobacter baumannii (Dortet et al, 2018a,b, 2019; Furniss et al, 2019), using routine MALDI mass spectrometer and its application into the detection of colistin-resistant S. enterica
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