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Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin

Susceptibility testing for colistin remains challenging primarily due to its inherent properties. We evaluated colistin stability in agar and reproducibility of colistin MICs obtained by agar dilution, broth macro- and micro-dilution and MIC gradient strips on 3–7 iterations of each method using cli...

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Autores principales: Turlej-Rogacka, Agata, Xavier, Basil Britto, Janssens, Lore, Lammens, Christine, Zarkotou, Olympia, Pournaras, Spyros, Goossens, Herman, Malhotra-Kumar, Surbhi
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Berlin Heidelberg 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5780530/
https://www.ncbi.nlm.nih.gov/pubmed/29177612
http://dx.doi.org/10.1007/s10096-017-3140-3
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author Turlej-Rogacka, Agata
Xavier, Basil Britto
Janssens, Lore
Lammens, Christine
Zarkotou, Olympia
Pournaras, Spyros
Goossens, Herman
Malhotra-Kumar, Surbhi
author_facet Turlej-Rogacka, Agata
Xavier, Basil Britto
Janssens, Lore
Lammens, Christine
Zarkotou, Olympia
Pournaras, Spyros
Goossens, Herman
Malhotra-Kumar, Surbhi
author_sort Turlej-Rogacka, Agata
collection PubMed
description Susceptibility testing for colistin remains challenging primarily due to its inherent properties. We evaluated colistin stability in agar and reproducibility of colistin MICs obtained by agar dilution, broth macro- and micro-dilution and MIC gradient strips on 3–7 iterations of each method using clinical Klebsiella pneumoniae (susceptible-CS, and resistant-CR, n = 2 each), mcr-harboring Escherichia coli (n = 2), and reference strains E. coli ATCC25922 and Pseudomonas aeruginosa ATCC27853. MICs for reference strains were not in the given range using Etest and broth microdilution (ATCC25922, 0.125 and 4 μg/ml, respectively). MICs of CR-1 and CR-2, and of the mcr-harboring E. coli showed high concordance between agar and broth dilution varying up to one 2-fold dilution. However, remarkable variations were observed on broth dilution with CS-1 and CS-2 (MIC range 0.25–32 and 0.5–64 μg/ml, respectively); whereas for agar dilution the MIC for both CS strains was 0.5 μg/ml in all the runs. MICs obtained by MIC gradient strips were lower than those obtained by dilution methods (1–2 dilutions for CS and mcr strains, and up to five dilutions for CR strains). To confirm uniform distribution of colistin in agar, a single strain was spotted in five different regions of the same plate. All spots showed concordant growth with maximum one dilution difference. No effect on MIC was found due to storage of colistin-containing agar plates for 7 days at 4 °C. In our hands, agar dilution was superior in terms of reproducibility and robustness, compared to broth dilution methods, for colistin MIC determination.
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spelling pubmed-57805302018-02-01 Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin Turlej-Rogacka, Agata Xavier, Basil Britto Janssens, Lore Lammens, Christine Zarkotou, Olympia Pournaras, Spyros Goossens, Herman Malhotra-Kumar, Surbhi Eur J Clin Microbiol Infect Dis Original Article Susceptibility testing for colistin remains challenging primarily due to its inherent properties. We evaluated colistin stability in agar and reproducibility of colistin MICs obtained by agar dilution, broth macro- and micro-dilution and MIC gradient strips on 3–7 iterations of each method using clinical Klebsiella pneumoniae (susceptible-CS, and resistant-CR, n = 2 each), mcr-harboring Escherichia coli (n = 2), and reference strains E. coli ATCC25922 and Pseudomonas aeruginosa ATCC27853. MICs for reference strains were not in the given range using Etest and broth microdilution (ATCC25922, 0.125 and 4 μg/ml, respectively). MICs of CR-1 and CR-2, and of the mcr-harboring E. coli showed high concordance between agar and broth dilution varying up to one 2-fold dilution. However, remarkable variations were observed on broth dilution with CS-1 and CS-2 (MIC range 0.25–32 and 0.5–64 μg/ml, respectively); whereas for agar dilution the MIC for both CS strains was 0.5 μg/ml in all the runs. MICs obtained by MIC gradient strips were lower than those obtained by dilution methods (1–2 dilutions for CS and mcr strains, and up to five dilutions for CR strains). To confirm uniform distribution of colistin in agar, a single strain was spotted in five different regions of the same plate. All spots showed concordant growth with maximum one dilution difference. No effect on MIC was found due to storage of colistin-containing agar plates for 7 days at 4 °C. In our hands, agar dilution was superior in terms of reproducibility and robustness, compared to broth dilution methods, for colistin MIC determination. Springer Berlin Heidelberg 2017-11-25 2018 /pmc/articles/PMC5780530/ /pubmed/29177612 http://dx.doi.org/10.1007/s10096-017-3140-3 Text en © The Author(s) 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Original Article
Turlej-Rogacka, Agata
Xavier, Basil Britto
Janssens, Lore
Lammens, Christine
Zarkotou, Olympia
Pournaras, Spyros
Goossens, Herman
Malhotra-Kumar, Surbhi
Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin
title Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin
title_full Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin
title_fullStr Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin
title_full_unstemmed Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin
title_short Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin
title_sort evaluation of colistin stability in agar and comparison of four methods for mic testing of colistin
topic Original Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5780530/
https://www.ncbi.nlm.nih.gov/pubmed/29177612
http://dx.doi.org/10.1007/s10096-017-3140-3
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