Optimization of the MALDIxin test for the rapid identification of colistin resistance in Klebsiella pneumoniae using MALDI-TOF MS. (3rd October 2019)

• Record Type: Journal Article
• Authors: Dortet, Laurent; Broda, Agnieszka; Bernabeu, Sandrine; Glupczynski, Youri; Bogaerts, Pierre; Bonnin, Rémy; Naas, Thierry; Filloux, Alain; Larrouy-Maumus, Gerald
• Is Part Of: Journal of antimicrobial chemotherapy. Volume 75:Number 1(2020)
• Page Start: 110
• Page End: 116
• Publication Date: 2019-10-03
• Subjects: Anti-infective agents -- Periodicals; Chemotherapy -- Periodicals; 615.58
• DOI: 10.1093/jac/dkz405
• Languages: English
• ISSNs: 0305-7453

Abstract

Abstract: Background: With the dissemination of carbapenemase producers, a revival of colistin was observed for the treatment of infections caused by MDR Gram-negatives. Unfortunately, the increasing usage of colistin led to the emergence of resistance. In Klebsiella pneumoniae, colistin resistance arises through addition of 4-amino-l -arabinose (l -Ara4N) or phosphoethanolamine (pEtN) to the native lipid A. The underlying mechanisms involve numerous chromosome-encoded genes or the plasmid-encoded pEtN transferase MCR. Currently, detection of colistin resistance is time-consuming since it still relies on MIC determination by broth microdilution. Recently, a rapid diagnostic test based on MALDI-TOF MS detection of modified lipid A was developed (the MALDIxin test) and tested on Escherichia coli and Acinetobacter baumannii . Objectives: Optimize the MALDIxin test for the rapid detection of colistin resistance in K. pneumoniae . Methods: This optimization consists of an additional mild-acid hydrolysis of 15 min in 1% acetic acid. The optimized method was tested on a collection of 81 clinical K. pneumoniae isolates, including 49 colistin-resistant isolates (45 with chromosome-encoded resistance, 3 with MCR-related resistance and 1 with both mechanisms). Results: The optimized method allowed the rapid (<30 min) identification of l -Ara4N- and pEtN-modified lipid A of K. pneumoniae, which are known to be the real triggers of polymyxin resistance. At the same time, it discriminates between chromosome-encoded and MCR-related polymyxin resistance. Conclusions: The MALDIxin test has the potential to become an accurate tool for the rapid determination of colistin resistance in clinically relevant Gram-negative bacteria.