scholarly journals Optimization of the MALDIxin test for the rapid identification of colistin resistance in Klebsiella pneumoniae using MALDI-TOF MS

2019 ◽  
Vol 75 (1) ◽  
pp. 110-116 ◽  
Author(s):  
Laurent Dortet ◽  
Agnieszka Broda ◽  
Sandrine Bernabeu ◽  
Youri Glupczynski ◽  
Pierre Bogaerts ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Lipid A ◽  
Rapid Determination ◽  
Rapid Identification ◽  
Colistin Resistance ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Underlying Mechanisms ◽  
Emergence Of Resistance ◽  
Tof Ms

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.

scholarly journals Resistance and Heteroresistance to Colistin in Pseudomonas aeruginosa Isolates from Wenzhou, China

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Jie Lin ◽  
Chunquan Xu ◽  
Renchi Fang ◽  
Jianming Cao ◽  
Xiucai Zhang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Population Analysis ◽  
Colistin Resistance ◽  
Content Type ◽  
Maldi Tof Ms ◽  
Expression Levels ◽  
Maldi Tof ◽  
Broth Microdilution Method ◽  
Tof Ms

ABSTRACT The goal was to investigate the mechanisms of colistin resistance and heteroresistance in Pseudomonas aeruginosa clinical isolates. Colistin resistance was determined by the broth microdilution method. Colistin heteroresistance was evaluated by population analysis profiling. Time-kill assays were also conducted. PCR sequencing was performed to detect the resistance genes among (hetero)resistant isolates, and quantitative real-time PCR assays were performed to determine their expression levels. Pulsed-field gel electrophoresis and multilocus sequence typing were performed. Lipid A characteristics were determined via matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS). Two resistant isolates and 9 heteroresistant isolates were selected in this study. Substitutions in PmrB were detected in 2 resistant isolates. Among heteroresistant isolates, 8 of 9 heteroresistant isolates had nonsynonymous PmrB substitutions, and 2 isolates, including 1 with a PmrB substitution, had PhoQ alterations. Correspondingly, the expression levels of pmrA or phoP were upregulated in PmrB- or PhoQ-substituted isolates. One isolate also found alterations in ParRS and CprRS. The transcript levels of the pmrH gene were observed to increase across all investigated isolates. MALDI-TOF MS showed additional 4-amino-4-deoxy-l-arabinose (l-Ara4N) moieties in lipid A profiles in (hetero)resistant isolates. In conclusion, both colistin resistance and heteroresistance in P. aeruginosa in this study mainly involved alterations of the PmrAB regulatory system. There were strong associations between mutations in specific genetic loci for lipid A synthesis and regulation of modifications to lipid A. The transition of colistin heteroresistance to resistance should be addressed in future clinical surveillance.

scholarly journals Establishment and Application of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry for Detection of Shewanella Genus

2021 ◽  
Vol 12 ◽  
Author(s):  
Keyi Yu ◽  
Zhenzhou Huang ◽  
Ying Li ◽  
Qingbo Fu ◽  
Lirong Lin ◽  
...  
Keyword(s):  
Laser Desorption ◽  
Rapid Identification ◽  
Species Level ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Type Strains ◽  
Tof Ms

Shewanella species are widely distributed in the aquatic environment and aquatic organisms. They are opportunistic human pathogens with increasing clinical infections reported in recent years. However, there is a lack of a rapid and accurate method to identify Shewanella species. We evaluated here matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for rapid identification of Shewanella. A peptide mass reference spectra (PMRS) database was constructed for the type strains of 36 Shewanella species. The main spectrum projection (MSP) cluster dendrogram showed that the type strains of Shewanella species can be effectively distinguished according to the different MS fingerprinting. The PMRS database was validated using 125 Shewanella test strains isolated from various sources and periods; 92.8% (n = 116) of the strains were correctly identified at the species level, compared with the results of multilocus sequence analysis (MLSA), which was previously shown to be a method for identifying Shewanella at the species level. The misidentified strains (n = 9) by MALDI-TOF MS involved five species of two groups, i.e., Shewanella algae–Shewanella chilikensis–Shewanella indica and Shewanella seohaensis–Shewanella xiamenensis. We then identified and defined species-specific biomarker peaks of the 36 species using the type strains and validated these selected biomarkers using 125 test strains. Our study demonstrated that MALDI-TOF MS was a reliable and powerful tool for the rapid identification of Shewanella strains at the species level.

scholarly journals Rapid identification of Streptomyces isolates by MALDI-TOF MS

2014 ◽  
Vol 169 (12) ◽  
pp. 940-947 ◽  
Author(s):  
Lotfi Loucif ◽  
Esma Bendjama ◽  
Djamila Gacemi-Kirane ◽  
Jean-Marc Rolain
Keyword(s):  
Rapid Identification ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

scholarly journals Rapid Identification of Microorganisms from Positive Blood Culture by MALDI-TOF MS After Short-Term Incubation on Solid Medium

2016 ◽  
Vol 74 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Antonio Curtoni ◽  
Raffaella Cipriani ◽  
Elisa Simona Marra ◽  
Anna Maria Barbui ◽  
Rossana Cavallo ◽  
...  
Keyword(s):  
Blood Culture ◽  
Positive Blood Culture ◽  
Solid Medium ◽  
Rapid Identification ◽  
Short Term ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

scholarly journals Rapid identification of respiratory bacterial pathogens from bronchoalveolar lavage fluid in cattle by MALDI-TOF MS

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Laura Van Driessche ◽  
Jade Bokma ◽  
Piet Deprez ◽  
Freddy Haesebrouck ◽  
Filip Boyen ◽  
...  
Keyword(s):  
Bronchoalveolar Lavage ◽  
Bronchoalveolar Lavage Fluid ◽  
Lavage Fluid ◽  
Turnaround Time ◽  
Rapid Identification ◽  
Antimicrobial Use ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tract Infections ◽  
Tof Ms

AbstractRespiratory tract infections are a major health problem and indication for antimicrobial use in cattle and in humans. Currently, most antimicrobial treatments are initiated without microbiological results, holding the risk of inappropriate first intention treatment. The main reason for this empirical treatment is the long turnaround time between sampling and availability of identification and susceptibility results. Therefore the objective of the present study was to develop a rapid identification procedure for pathogenic respiratory bacteria in bronchoalveolar lavage fluid (BALf) samples from cattle by MALDI-TOF MS, omitting the cultivation step on agar plates to reduce the turnaround time between sampling and identification of pathogens. The effects of two different liquid growth media and various concentrations of bacitracin were determined to allow optimal growth of Pasteurellaceae and minimise contamination. The best procedure was validated on 100 clinical BALf samples from cattle with conventional bacterial culture as reference test. A correct identification was obtained in 73% of the samples, with 59.1% sensitivity (Se) (47.2–71.0%) and 100% specificity (Sp) (100–100%) after only 6 hours of incubation. For pure and dominant culture samples, the procedure was able to correctly identify 79.2% of the pathogens, with a sensitivity (Se) of 60.5% (45.0–76.1%) and specificity (Sp) of 100% (100–100%). In mixed culture samples, containing ≥2 clinically relevant pathogens, one pathogen could be correctly identified in 57% of the samples with 57.1% Se (38.8–75.5%) and 100% Sp (100–100%). In conclusion, MALDI-TOF MS is a promising tool for rapid pathogen identification in BALf. This new technique drastically reduces turnaround time and may be a valuable decision support tool to rationalize antimicrobial use.

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