Summation of peaks and L34 ribosomal protein in the presence and absence of antibiotics enables susceptibility testing using MALDI-TOF mass spectrometry in 2h from Escherichia coli-positive blood cultures
Enferm Infecc Microbiol Clin (Engl Ed). 2019 Apr;37(4):244-250.
doi: 10.1016/j.eimc.2018.06.017.
Epub 2018 Sep 17.
[Article in
English,
Spanish]
Affiliations
- 1 Research Group on Clinical Microbiology and Parasitology and Antimicrobial Resistance (IIMD-16), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, CSIC, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain.
- 2 Departamento de Informática y Automática, Universidad de Salamanca, Salamanca, Spain.
- 3 Research Group on Clinical Microbiology and Parasitology and Antimicrobial Resistance (IIMD-16), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, CSIC, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain; Servicio de Microbiología y Parasitología, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain.
- 4 Research Group on Clinical Microbiology and Parasitology and Antimicrobial Resistance (IIMD-16), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, CSIC, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain; Servicio de Microbiología y Parasitología, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain; Departamento de Ciencias Biomédicas y del Diagnóstico, Universidad de Salamanca, Salamanca, Spain. Electronic address: jlmubel@usal.es.
- 5 Servicio de Análisis Clínicos, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain; Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Salamanca, Spain; Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, CSIC, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain.
- 6 Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca, CSIC, Complejo Asistencial Universitario de Salamanca, Salamanca, Spain.
Abstract
Introduction:
We have developed a MALDI-TOF-mediated phenotypic method, which determines antibiotic susceptibility (AS) from positive blood cultures (BCs) in 2h. We developed a software for process automation. We report results on Escherichia coli-positive BCs with cefotaxime (CTX) and ciprofloxacin (CIP).
Methods:
We studied CIP and CTX activity in 18 and 17 real E. coli-positive BCs, and in 56 and 45 spiked BCs, respectively. Positive BCs were incubated for 2h without any antibiotics, and with 2mg/l and 4mg/l of CIP and CTX. The extraction was performed using ethanol/formic acid. Spectra were processed with specifically developed software which compares the peaks' intensity and the size of specific peaks.
Results:
The set cut-off point was a 3-fold decrease in the summation of all peaks and/or the 5382m/z peak value (ribosomal protein L34). In simulated BCs, the correlation of CIP 2mg/l and 4mg/l with Etest® was 94.6% and 98.2%, respectively; for CTX 2mg/l and 4mg/l, this correlation was 95.6%. In real BCs, the correlations were 100% for CIP (2mg/l and 4mg/l) and 88.2% and 94.1% for CTX 2mg/l and 4mg/l, respectively. Resistant isolates were always correctly classified.
Conclusion:
This method provides accurate, fast and inexpensive AS information. The method can be automated, making it easier to implement in a microbiology laboratory routine.
Keywords:
Antibiotic susceptibility; Blood cultures; Espectrometría de masas MALDI-TOF; Hemocultivos; MALDI-TOF MS; Sensibilidad a antimicrobianos.
Copyright © 2018 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.
MeSH terms
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Anti-Bacterial Agents / pharmacology*
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Bacteriological Techniques / methods
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Blood Culture
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Cefotaxime / pharmacology*
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Ciprofloxacin / pharmacology*
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Escherichia coli / drug effects*
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Humans
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Microbial Sensitivity Tests
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Ribosomal Proteins / analysis*
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Software
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Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization*
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Time Factors
Substances
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Anti-Bacterial Agents
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Ribosomal Proteins
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ribosomal protein L34
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Ciprofloxacin
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Cefotaxime