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Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii

BACKGROUND: Acinetobacter baumannii is a nosocomial pathogen which is establishing as a major cause of morbidity and mortality within the healthcare community. The success of this pathogen is largely due to its ability to rapidly gain resistance to antimicrobial therapies and its capability to persi...

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Autores principales: Raible, Kevin M., Sen, Bhaswati, Law, Nancy, Bias, Tiffany E., Emery, Christopher L., Ehrlich, Garth D., Joshi, Suresh G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5691885/
https://www.ncbi.nlm.nih.gov/pubmed/29145853
http://dx.doi.org/10.1186/s12941-017-0248-3
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author Raible, Kevin M.
Sen, Bhaswati
Law, Nancy
Bias, Tiffany E.
Emery, Christopher L.
Ehrlich, Garth D.
Joshi, Suresh G.
author_facet Raible, Kevin M.
Sen, Bhaswati
Law, Nancy
Bias, Tiffany E.
Emery, Christopher L.
Ehrlich, Garth D.
Joshi, Suresh G.
author_sort Raible, Kevin M.
collection PubMed
description BACKGROUND: Acinetobacter baumannii is a nosocomial pathogen which is establishing as a major cause of morbidity and mortality within the healthcare community. The success of this pathogen is largely due to its ability to rapidly gain resistance to antimicrobial therapies and its capability to persist in an abiotic environment through the production of a biofilm. Our tertiary-care hospital has showed high incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates. METHODS: In this study we explore both genotypic and phenotypic properties of 26 CRAB isolates: 16 isolates were collected from January 2010 to March 2011, and 10 were collected between February and May 2015. RESULTS: We determined that all 26 CRAB isolates possessed multiple β-lactamase genes, including genes from Groups A, C, and D. Specifically, 42% of the isolates possesses the potentially plasmid-borne genes of OXA-23-like or OXA-40-like β-lactamase. The presence of mobile gene element integron cassettes and/or integrases in 88% of the isolates suggests a possible mechanism of dissemination of antibiotic resistance genes. Additionally, the location of insertion sequence (IS) ISAba1 in promotor region of of the OXA-51-like, ADC-7, and ampC genes was confirmed. Multilocus sequence typing (MLST) demonstrated that all 26 CRAB isolates were either sequence type (ST)-229 or ST-2. Interestingly, ST-2 went from being the minority CRAB strain in the 2010–2011 isolates to the predominant strain in the 2015 isolates (from 32 to 90%). We show that the ST-2 strains have an enhanced ability to produce biofilms in comparison to the ST-229 strains, and this fact has potentially led to more successful colonization of the clinical environment over time. CONCLUSIONS: This study provides a longitudinal genetic and phenotypic survey of two CRAB sequence types, and suggests how their differing phenotypes may interact with the selective pressures of a hospital setting effecting strain dominance over a 5-year period. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12941-017-0248-3) contains supplementary material, which is available to authorized users.
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spelling pubmed-56918852017-11-24 Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii Raible, Kevin M. Sen, Bhaswati Law, Nancy Bias, Tiffany E. Emery, Christopher L. Ehrlich, Garth D. Joshi, Suresh G. Ann Clin Microbiol Antimicrob Research BACKGROUND: Acinetobacter baumannii is a nosocomial pathogen which is establishing as a major cause of morbidity and mortality within the healthcare community. The success of this pathogen is largely due to its ability to rapidly gain resistance to antimicrobial therapies and its capability to persist in an abiotic environment through the production of a biofilm. Our tertiary-care hospital has showed high incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates. METHODS: In this study we explore both genotypic and phenotypic properties of 26 CRAB isolates: 16 isolates were collected from January 2010 to March 2011, and 10 were collected between February and May 2015. RESULTS: We determined that all 26 CRAB isolates possessed multiple β-lactamase genes, including genes from Groups A, C, and D. Specifically, 42% of the isolates possesses the potentially plasmid-borne genes of OXA-23-like or OXA-40-like β-lactamase. The presence of mobile gene element integron cassettes and/or integrases in 88% of the isolates suggests a possible mechanism of dissemination of antibiotic resistance genes. Additionally, the location of insertion sequence (IS) ISAba1 in promotor region of of the OXA-51-like, ADC-7, and ampC genes was confirmed. Multilocus sequence typing (MLST) demonstrated that all 26 CRAB isolates were either sequence type (ST)-229 or ST-2. Interestingly, ST-2 went from being the minority CRAB strain in the 2010–2011 isolates to the predominant strain in the 2015 isolates (from 32 to 90%). We show that the ST-2 strains have an enhanced ability to produce biofilms in comparison to the ST-229 strains, and this fact has potentially led to more successful colonization of the clinical environment over time. CONCLUSIONS: This study provides a longitudinal genetic and phenotypic survey of two CRAB sequence types, and suggests how their differing phenotypes may interact with the selective pressures of a hospital setting effecting strain dominance over a 5-year period. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12941-017-0248-3) contains supplementary material, which is available to authorized users. BioMed Central 2017-11-16 /pmc/articles/PMC5691885/ /pubmed/29145853 http://dx.doi.org/10.1186/s12941-017-0248-3 Text en © The Author(s) 2017 Open AccessThis 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. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Raible, Kevin M.
Sen, Bhaswati
Law, Nancy
Bias, Tiffany E.
Emery, Christopher L.
Ehrlich, Garth D.
Joshi, Suresh G.
Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii
title Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii
title_full Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii
title_fullStr Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii
title_full_unstemmed Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii
title_short Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii
title_sort molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant acinetobacter baumannii
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5691885/
https://www.ncbi.nlm.nih.gov/pubmed/29145853
http://dx.doi.org/10.1186/s12941-017-0248-3
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