A rapid diagnostic workflow for cefotaxime-resistant Escherichia coli and Klebsiella pneumoniae detection from blood cultures by MALDI-TOF mass spectrometry.

Elena De Carolis,Brunella Posteraro,Ivana Palucci,Tiziana D’Inzeo,Enrica Mello,Maurizio Sanguinetti,Teresa Spanu,Giulia De Angelis,Domenico Nagel,Antonietta Vella,Silvia Paoletti,Massimiliano Galdiero

doi:10.1371/journal.pone.0185935

Elena De Carolis, Brunella Posteraro + Show 10 more

Open Access

https://doi.org/10.1371/journal.pone.0185935

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Abstract

BackgroundNowadays, the global spread of resistance to oxyimino-cephalosporins in Enterobacteriaceae implies the need for novel diagnostics that can rapidly target resistant organisms from these bacterial species.MethodsIn this study, we developed and evaluated a Direct Mass Spectrometry assay for Beta-Lactamase (D-MSBL) that allows direct identification of (oxyimino)cephalosporin-resistant Escherichia coli or Klebsiella pneumoniae from positive blood cultures (BCs), by using the matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) technology.ResultsThe D-MSBL assay was performed on 93 E. coli or K. pneumoniae growing BC samples that were shortly co-incubated with cefotaxime (CTX) as the indicator cephalosporin. Susceptibility and resistance defining peaks from the samples’ mass spectra were analyzed by a novel algorithm for bacterial organism classification. The D-MSBL assay allowed discrimination between E. coli and K. pneumoniae that were resistant or susceptible to CTX with a sensitivity of 86.8% and a specificity of 98.2%.ConclusionThe proposed algorithm-based D-MSBL assay, if integrated in the routine laboratory diagnostic workflow, may be useful to enhance the establishment of appropriate antibiotic therapy and to control the threat of oxyimino-cephalosporin resistance in hospital.

Highlights

In the last decades, bloodstream infections caused by the Enterobacteriaceae family-members Escherichia coli and Klebsiella pneumoniae showing resistance to third-generation oxyiminocephalosporin antibiotics [1,2], mainly to cefotaxime (CTX) [3], have increased
The Direct Mass Spectrometry assay for Beta-Lactamase (D-MSBL) assay was performed on 93 E. coli or K. pneumoniae growing blood cultures (BCs) samples that were shortly co-incubated with cefotaxime (CTX) as the indicator cephalosporin
The proposed algorithm-based D-MSBL assay, if integrated in the routine laboratory diagnostic workflow, may be useful to enhance the establishment of appropriate antibiotic therapy and to control the threat of oxyimino-cephalosporin resistance in hospital

Summary

Introduction

Bloodstream infections caused by the Enterobacteriaceae family-members Escherichia coli and Klebsiella pneumoniae showing resistance to third-generation oxyiminocephalosporin antibiotics [1,2], mainly to cefotaxime (CTX) [3], have increased. This has a negative impact on the infection-related mortality rates and hospital costs [4], and it is associated with a delay in the administration of appropriate antibiotic therapy [5]. Resistant isolates produce extended-spectrum β-lactamases (ESBLs), the plasmid-mediated enzymes that can confer non-susceptibility to cefotaxime and other oxyimino-cephalosporins (e.g., ceftazidime) and to monobactams [7]. The global spread of resistance to oxyimino-cephalosporins in Enterobacteriaceae implies the need for novel diagnostics that can rapidly target resistant organisms from these bacterial species

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