A rapid MALDI‐TOF mass spectrometry‐based method for colistin susceptibility testing in Escherichia coli

Abstract

Colistin is recognized as a last-resort treatment option against multi-drug resistant bacteria including carbapenem-resistant Enterobacteriaceae (CRE). However, the plasmid-mediated colistin-resistance gene mcr-1 has been reported globally resulting in an increase of colistin-resistant bacteria. A quick and accurate method for determining the pathogen resistance of colistin is therefore crucial in the clinic. Matrix-assisted laser desorption/ionization time-offlight mass spectrometry (MALDI-TOF MS) is a potential tool forto be applied for antimicrobial susceptibility testing. We compared the growth of Escherichia coli strains in the presence or absence of colistin. Automated analyses of the spectra were performed with a prototype software tool written with package R. Three mcr-1-positive and six mcr-1-negative E. coli were used for establishing the model to obtain the optimal incubation time, the breakpoint concentration of colistin and cut-off of the relative growth (RG) value. The distinction between susceptible and resistant strains was already noticeable after 2 h of incubation. The best separation between the susceptible and resistant strains was achieved at a concentration of 4 µg ml -1 and a relative growth cutoff value of 0.6. Application of the model for the analysis of 128 E. coli isolates, a sensitivity of 97.4% and a specificity of 88.2% were achieved compared with colistin MIC results. The rapid MALDI-TOF MSbased method approach is simple to set-up, uses a short incubation time, and had excellent outcomes with respect to sensitivity and specificity for colistin sensitivity testing in Escherichia coli.

Antimicrobial Susceptibility Testing for Colistin: Extended Application of Novel Quantitative and Morphologic Assay Using Scanning Electron Microscopy

“…Interestingly, there have been several advances related to imaging-based methodologies that utilize optical sensors, bright-feld microscopy, and combinations of optical sensors with other technologies [21]. Some of these techniques have allowed the determination of AST results in less than 5 hours, but remain difcult to disseminate as a replacement for BMD in routine practice due to performance issues of great importance and high cost [22,23]. Overall, BMD remains the most reliable method for determining the susceptibility of Colistin.…”

First‐in‐human application of double‐stranded RNA bacteriophage in the treatment of pulmonary Pseudomonas aeruginosa infection

“…Clinical strains of the patient during phage therapy were isolated from the patient's respiratory secretions, and the strains were isolated using MacConkey Agar plates, identified by mass spectrometry with Bruker MALDI (Matrix‐assisted laser desorption/ionization) Biotyper Rapid Microbial Identification System (Bruker Daltonik GmbH) and cultured in Luria‐Bertani medium at 37°C (Li et al, 2022 ; Yo et al, 2022 ). The antibiotic sensitivity test was performed by the agar disk diffusion method with reference to the Clinical and Laboratory Standards Institute (CLSI) standard.…”

Metabolism-Triggered Plasmonic Nanosensor for Bacterial Detection and Antimicrobial Susceptibility Testing of Clinical Isolates

“…As a result, efforts have been made to develop rapid and efficient phenotypic AST assays that utilize various bacterial phenotypic features such as physiology, size, number, and morphology. 12,18−20 These assays could achieve rapid AST by monitoring the differences in bacterial phenotypic features after incubation with or without antibiotics using techniques like optical detection, 21−23 flow cytometry, 24 mass spectrometry, 25 gene-based assays, 15,26−28 and plasmonic nanosensors. 29−31 Among these, a plasmonic nanosensor based on gold nanoparticles (AuNPs) is a good candidate owing to its convenient operation and unnecessary bulky instruments.…”

“…In the past few decades, a number of new AST strategies have been continuously proposed. − Genotypic AST methods are attractive alternatives as they allow for sensitive and rapid identification (within 2 h) without the need for extended cultures. − However, their effectiveness is limited by the fact that only a few genes are significantly associated with phenotypic resistance, and they require expensive reagents, specialized equipment, and trained personnel. As a result, efforts have been made to develop rapid and efficient phenotypic AST assays that utilize various bacterial phenotypic features such as physiology, size, number, and morphology. ,− These assays could achieve rapid AST by monitoring the differences in bacterial phenotypic features after incubation with or without antibiotics using techniques like optical detection, − flow cytometry, mass spectrometry, gene-based assays, ,− and plasmonic nanosensors. − Among these, a plasmonic nanosensor based on gold nanoparticles (AuNPs) is a good candidate owing to its convenient operation and unnecessary bulky instruments. ,− It offers a straightforward naked-eye readout, holding great promise for applications outside of a laboratory setting.…”