Detection of Colistin Resistance in Using MALDIxin Test on the Routine MALDI Biotyper Sirius Mass Spectrometer.

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 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 using the MALDxin test on the routine matrix-assisted laser desorption ionization (MALDI) Biotyper Sirius system.