Two-site study on performances of a commercially available MALDI-TOF MS-based assay for the detection of colistin resistance in Escherichia coli

AbstractColistin is a last resort drug for the treatment of multiple drug-resistant (MDR) Gram-negative bacterial infections. Rapid methods to detect resistance are highly desirable. Here, we evaluated the performance of a commercially available MALDI-TOF MS-based assay for colistin resistance testing inEscherichia coli at two different sites. Ninety clinicalE. coli isolates were provided by France and tested in Germany and UK using a MALDI-TOF MS-based colistin resistance assay. Lipid A molecules of the bacterial cell membrane were extracted using the MBT Lipid Xtract Kit ™ (RUO; Bruker Daltonics, Germany). Spectra acquisition and evaluation were performed by the MBT HT LipidART Module of MBT Compass HT (RUO; Bruker Daltonics) on a MALDI Biotyper® sirius system (Bruker Daltonics) in negative ion mode. Phenotypic colistin resistance was determined by broth microdil ution (MICRONAUT MIC-Strip Colistin, Bruker Daltonics) and used as a reference. Comparing the results of the MALDI-TOF MS-based colistin resistance assay with the data of the phenotypic reference method for the UK, sensitivity and specificity for the detection of colistin resistance were 97.1% (33/3 4) and 96.4% (53/55), respectively. Germany showed 97.1% (33/34) sensitivity and 100% (55/55) specificity for the detection of colistin resistance by MALDI-TOF MS. Applying the MBT Lipid Xtract™ Kit in combination with MALDI-TOF MS and dedicated software showed excellent performances forE. coli. Analytical and clin...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research