Fast and robust detection of colistin resistance in Escherichia coli using the MALDI Biotyper Sirius mass spectrometry system

Abstract

11 3 EA7361 "Structure, dynamic, function and expression of broad spectrum β-lactamases", ABSTRACT 31 Polymyxin antibiotics are a last-line treatment for multidrug-resistant Gram-negative 32 bacteria. However, the emergence of colistin resistance, including the spread of mobile mcr 33 genes, necessitates the development of improved diagnostics for the detection of colistin-34 resistant organisms in hospital settings. The recently developed MALDIxin test enables 35 detection of colistin resistance by MALDI-TOF mass spectrometry in less than 15 minutes 36 but is not optimized for the mass spectrometers commonly found in clinical microbiology 37 laboratories. In this study, we adapted the MALDIxin test for the MALDI Biotyper Sirius 38 MALDI-TOF mass spectrometry system (Bruker Daltonics). We optimized the sample 39 preparation protocol using a set of 6 MCR-expressing Escherichia coli clones and validated the 40 assay with a collection of 40 E. coli clinical isolates, including 19 MCR producers, 12 41 chromosomally-resistant isolates and 9 polymyxin-susceptible isolates. We calculated 42 Polymyxin resistance ratio (PRR) values from the acquired spectra; a PRR value of zero, 43 indicating polymyxin susceptibility, was obtained for all colistin-susceptible E. coli isolates, 44 whereas positive PRR values, indicating resistance to polymyxins, were obtained for all 45 resistant strains independent of the genetic basis of resistance. Thus, we report a preliminary 46 feasibility study showing that an optimized version of the MALDIxin test, adapted for the 47 routine MALDI Biotyper Sirius, provides an unbiased, fast, reliable, cost-effective and high-48 throughput way of detecting colistin resistance in clinical E. coli isolates.49

Rapid glycosyl‐inositol‐phospho‐ceramide fingerprint from filamentous fungal pathogens using the MALDI Biotyper Sirius system

“…For example, extraction and purification of bacterial lipid A, which is the anchor of the lipopolysaccharide found in the outer membrane of Gram‐negative bacteria, was a challenging and time‐consuming process 16–22 . In that case, for bacterial lipid A analysis using MALDI‐TOFMS, we and others have recently developed methods to ease considerably its characterization based on either lipid micro‐extraction prior to MALDI‐TOFMS analysis or direct detection of lipid A molecules and their modifications on heat‐inactivated bacteria using routine MALDI‐TOFMS 23–32 …”