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Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena

BACKGROUND: Enterobacter aerogenes and Klebsiella pneumoniae are common isolates in clinical microbiology and important as producers of extended spectrum β-lactamases (ESBL). The discrimination between both species, which is routinely based on biochemical characteristics, is generally accepted to be...

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Autores principales: Claeys, Geert, De Baere, Thierry, Wauters, Georges, Vandecandelaere, Patricia, Verschraegen, Gerda, Muylaert, An, Vaneechoutte, Mario
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2004
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC544577/
https://www.ncbi.nlm.nih.gov/pubmed/15619329
http://dx.doi.org/10.1186/1471-2180-4-49
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author Claeys, Geert
De Baere, Thierry
Wauters, Georges
Vandecandelaere, Patricia
Verschraegen, Gerda
Muylaert, An
Vaneechoutte, Mario
author_facet Claeys, Geert
De Baere, Thierry
Wauters, Georges
Vandecandelaere, Patricia
Verschraegen, Gerda
Muylaert, An
Vaneechoutte, Mario
author_sort Claeys, Geert
collection PubMed
description BACKGROUND: Enterobacter aerogenes and Klebsiella pneumoniae are common isolates in clinical microbiology and important as producers of extended spectrum β-lactamases (ESBL). The discrimination between both species, which is routinely based on biochemical characteristics, is generally accepted to be straightforward. Here we report that genotypically unrelated strains of E. aerogenes can be misidentified as K. pneumoniae by routine laboratories using standard biochemical identification and using identification automates. RESULTS: Ten clinical isolates, identified as K. pneumoniae or K. terrigena with the routinely used biochemical tests and with API-20E, were identified as E. aerogenes by tDNA-PCR – an identification that was confirmed by 16S rRNA gene sequencing for five of these isolates. Misidentification also occurred when using the automated identification systems Vitek 2 and Phoenix, and was due to delayed positivity for ornithine decarboxylase and motility. Subculture and prolonged incubation resulted in positive results for ornithine decarboxylase and for motility. It could be shown by RAPD-analysis that the E. aerogenes strains belonged to different genotypes. CONCLUSIONS: Clinical E. aerogenes isolates can be easily misidentified as Klebsiella due to delayed positivity for ornithine decarboxylase and motility. The phenomenon may be widespread, since it was shown to occur among genotypically unrelated strains from different hospitals and different isolation dates. A useful clue for correct identification is the presence of an inducible β-lactamase, which is highly unusual for K. pneumoniae. In several instances, the use of genotypic techniques like tDNA-PCR may circumvent problems of phenotypic identification.
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spelling pubmed-5445772005-01-16 Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena Claeys, Geert De Baere, Thierry Wauters, Georges Vandecandelaere, Patricia Verschraegen, Gerda Muylaert, An Vaneechoutte, Mario BMC Microbiol Methodology Article BACKGROUND: Enterobacter aerogenes and Klebsiella pneumoniae are common isolates in clinical microbiology and important as producers of extended spectrum β-lactamases (ESBL). The discrimination between both species, which is routinely based on biochemical characteristics, is generally accepted to be straightforward. Here we report that genotypically unrelated strains of E. aerogenes can be misidentified as K. pneumoniae by routine laboratories using standard biochemical identification and using identification automates. RESULTS: Ten clinical isolates, identified as K. pneumoniae or K. terrigena with the routinely used biochemical tests and with API-20E, were identified as E. aerogenes by tDNA-PCR – an identification that was confirmed by 16S rRNA gene sequencing for five of these isolates. Misidentification also occurred when using the automated identification systems Vitek 2 and Phoenix, and was due to delayed positivity for ornithine decarboxylase and motility. Subculture and prolonged incubation resulted in positive results for ornithine decarboxylase and for motility. It could be shown by RAPD-analysis that the E. aerogenes strains belonged to different genotypes. CONCLUSIONS: Clinical E. aerogenes isolates can be easily misidentified as Klebsiella due to delayed positivity for ornithine decarboxylase and motility. The phenomenon may be widespread, since it was shown to occur among genotypically unrelated strains from different hospitals and different isolation dates. A useful clue for correct identification is the presence of an inducible β-lactamase, which is highly unusual for K. pneumoniae. In several instances, the use of genotypic techniques like tDNA-PCR may circumvent problems of phenotypic identification. BioMed Central 2004-12-24 /pmc/articles/PMC544577/ /pubmed/15619329 http://dx.doi.org/10.1186/1471-2180-4-49 Text en Copyright © 2004 Claeys et al; licensee BioMed Central Ltd.
spellingShingle Methodology Article
Claeys, Geert
De Baere, Thierry
Wauters, Georges
Vandecandelaere, Patricia
Verschraegen, Gerda
Muylaert, An
Vaneechoutte, Mario
Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena
title Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena
title_full Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena
title_fullStr Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena
title_full_unstemmed Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena
title_short Extended-Spectrum β-lactamase (ESBL) producing Enterobacter aerogenes phenotypically misidentified as Klebsiella pneumoniae or K. terrigena
title_sort extended-spectrum β-lactamase (esbl) producing enterobacter aerogenes phenotypically misidentified as klebsiella pneumoniae or k. terrigena
topic Methodology Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC544577/
https://www.ncbi.nlm.nih.gov/pubmed/15619329
http://dx.doi.org/10.1186/1471-2180-4-49
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