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Epidemiological MIC cut-off values for tigecycline calculated from Etest MIC values using normalized resistance interpretation

Kronvall, G ; Karlsson, I ; Walder, Mats LU ; Sorberg, M and Nilsson, LE (2006) In Journal of Antimicrobial Chemotherapy 57(3). p.498-505
Abstract
Objectives: To apply the normalized resistance interpretation (NRI) method to Etest MIC results which have higher precision than conventional log(2) dilution MIC tests due to the inclusion of intermediate values. If successful, NRI might provide an objective tool for the definition of epidemiological MIC cut-off values. Methods: MICs of tigecycline and other antimicrobial agents were determined for 4771 clinical isolates comprising five Gram-positive and 13 Gram-negative species or species groups using the Etest. Histograms of MIC values were constructed for each species and NRI calculations were applied to them. An upper MIC limit of 2.5 SD above the theoretical mean of the normalized distribution was used for setting the epidemiological... (More)
Objectives: To apply the normalized resistance interpretation (NRI) method to Etest MIC results which have higher precision than conventional log(2) dilution MIC tests due to the inclusion of intermediate values. If successful, NRI might provide an objective tool for the definition of epidemiological MIC cut-off values. Methods: MICs of tigecycline and other antimicrobial agents were determined for 4771 clinical isolates comprising five Gram-positive and 13 Gram-negative species or species groups using the Etest. Histograms of MIC values were constructed for each species and NRI calculations were applied to them. An upper MIC limit of 2.5 SD above the theoretical mean of the normalized distribution was used for setting the epidemiological cut-off values. Results: Calculated cut-off values for wild-type strains were between 0.11 and 0.96 mg/L for Gram-positive species, and between 0.44 and 8.3 mg/L for Gram-negative species, except for Pseudomonas aeruginosa, which had a cut-off value of 450 mg/L, consistent with earlier reports on the lack of activity of tigecycline against this species. Conclusions: NRI offers an objective method for the analysis of MICs produced using Etests and the determination of epidemiological MIC cut-off values. (Less)
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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
drug resistance, wild-type MIC distributions, clinical microbiology, antimicrobial susceptibility tests, MIC breakpoints
in
Journal of Antimicrobial Chemotherapy
volume
57
issue
3
pages
498 - 505
publisher
Oxford University Press
external identifiers
  • wos:000235282500014
  • pmid:16410264
  • scopus:32644438347
ISSN
1460-2091
DOI
10.1093/jac/dki489
language
English
LU publication?
yes
id
8ccadaaf-b6f6-40af-940a-065dc9416dec (old id 693624)
date added to LUP
2016-04-01 12:30:23
date last changed
2020-12-08 04:06:20
@article{8ccadaaf-b6f6-40af-940a-065dc9416dec,
  abstract     = {Objectives: To apply the normalized resistance interpretation (NRI) method to Etest MIC results which have higher precision than conventional log(2) dilution MIC tests due to the inclusion of intermediate values. If successful, NRI might provide an objective tool for the definition of epidemiological MIC cut-off values. Methods: MICs of tigecycline and other antimicrobial agents were determined for 4771 clinical isolates comprising five Gram-positive and 13 Gram-negative species or species groups using the Etest. Histograms of MIC values were constructed for each species and NRI calculations were applied to them. An upper MIC limit of 2.5 SD above the theoretical mean of the normalized distribution was used for setting the epidemiological cut-off values. Results: Calculated cut-off values for wild-type strains were between 0.11 and 0.96 mg/L for Gram-positive species, and between 0.44 and 8.3 mg/L for Gram-negative species, except for Pseudomonas aeruginosa, which had a cut-off value of 450 mg/L, consistent with earlier reports on the lack of activity of tigecycline against this species. Conclusions: NRI offers an objective method for the analysis of MICs produced using Etests and the determination of epidemiological MIC cut-off values.},
  author       = {Kronvall, G and Karlsson, I and Walder, Mats and Sorberg, M and Nilsson, LE},
  issn         = {1460-2091},
  language     = {eng},
  number       = {3},
  pages        = {498--505},
  publisher    = {Oxford University Press},
  series       = {Journal of Antimicrobial Chemotherapy},
  title        = {Epidemiological MIC cut-off values for tigecycline calculated from Etest MIC values using normalized resistance interpretation},
  url          = {http://dx.doi.org/10.1093/jac/dki489},
  doi          = {10.1093/jac/dki489},
  volume       = {57},
  year         = {2006},
}