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Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency

BACKGROUND: The ability of pathogens to adapt to the widely used biocide, triclosan, varies substantially. The purpose of the study was to examine bacterial adaptation over an extended period of time to low increments of triclosan concentrations. Focus was two human pathogens, S. aureus and L. monoc...

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Autores principales: Nielsen, Lene Nørby, Larsen, Marianne Halberg, Skovgaard, Sissel, Kastbjerg, Vicky, Westh, Henrik, Gram, Lone, Ingmer, Hanne
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733935/
https://www.ncbi.nlm.nih.gov/pubmed/23898801
http://dx.doi.org/10.1186/1471-2180-13-177
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author Nielsen, Lene Nørby
Larsen, Marianne Halberg
Skovgaard, Sissel
Kastbjerg, Vicky
Westh, Henrik
Gram, Lone
Ingmer, Hanne
author_facet Nielsen, Lene Nørby
Larsen, Marianne Halberg
Skovgaard, Sissel
Kastbjerg, Vicky
Westh, Henrik
Gram, Lone
Ingmer, Hanne
author_sort Nielsen, Lene Nørby
collection PubMed
description BACKGROUND: The ability of pathogens to adapt to the widely used biocide, triclosan, varies substantially. The purpose of the study was to examine bacterial adaptation over an extended period of time to low increments of triclosan concentrations. Focus was two human pathogens, S. aureus and L. monocytogenes that previously have displayed inherent high and low adaptability, respectively. RESULTS: Three strains of L. monocytogenes and two strains of S. aureus including the community-acquired USA300 were exposed to increasing, sub-lethal concentrations of triclosan in triclosan-containing agar gradients. Following 25 days of exposure on agar plates to sub-lethal concentrations of triclosan with a twofold concentration increase every second day, minimum inhibitory concentration (MIC) for S. aureus increased from 0.125 (8325–4) and 0.0625 (USA 300) mg/L to 4 mg/L. The MIC of all three L. monocytogenes strains was initially 4 mg/L and remained unaltered by the exposure. The adapted S. aureus isolates retained normal colony size but displayed increased expression of fabI encoding an essential enzyme in bacterial fatty acid synthesis. Also, they displayed decreased or no expression of the virulence associated agrC of the agr quorum sensing system. While most adapted strains of USA300 carried mutations in fabI, none of the adapted strains of 8325–4 did. CONCLUSIONS: Adaptability to triclosan varies substantially between Gram positive human pathogens. S. aureus displayed an intrinsically lower MIC for triclosan compared to L. monocytogenes but was easily adapted leading to the same MIC as L. monocytogenes. Even though all adapted S. aureus strains over-expressed fabI and eliminated expression of the agr quorum sensing system, adaptation in USA300 involved fabI mutations whereas this was not the case for 8325–4. Thus, adaptation to triclosan by S. aureus appears to involve multiple genetic pathways.
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spelling pubmed-37339352013-08-06 Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency Nielsen, Lene Nørby Larsen, Marianne Halberg Skovgaard, Sissel Kastbjerg, Vicky Westh, Henrik Gram, Lone Ingmer, Hanne BMC Microbiol Research Article BACKGROUND: The ability of pathogens to adapt to the widely used biocide, triclosan, varies substantially. The purpose of the study was to examine bacterial adaptation over an extended period of time to low increments of triclosan concentrations. Focus was two human pathogens, S. aureus and L. monocytogenes that previously have displayed inherent high and low adaptability, respectively. RESULTS: Three strains of L. monocytogenes and two strains of S. aureus including the community-acquired USA300 were exposed to increasing, sub-lethal concentrations of triclosan in triclosan-containing agar gradients. Following 25 days of exposure on agar plates to sub-lethal concentrations of triclosan with a twofold concentration increase every second day, minimum inhibitory concentration (MIC) for S. aureus increased from 0.125 (8325–4) and 0.0625 (USA 300) mg/L to 4 mg/L. The MIC of all three L. monocytogenes strains was initially 4 mg/L and remained unaltered by the exposure. The adapted S. aureus isolates retained normal colony size but displayed increased expression of fabI encoding an essential enzyme in bacterial fatty acid synthesis. Also, they displayed decreased or no expression of the virulence associated agrC of the agr quorum sensing system. While most adapted strains of USA300 carried mutations in fabI, none of the adapted strains of 8325–4 did. CONCLUSIONS: Adaptability to triclosan varies substantially between Gram positive human pathogens. S. aureus displayed an intrinsically lower MIC for triclosan compared to L. monocytogenes but was easily adapted leading to the same MIC as L. monocytogenes. Even though all adapted S. aureus strains over-expressed fabI and eliminated expression of the agr quorum sensing system, adaptation in USA300 involved fabI mutations whereas this was not the case for 8325–4. Thus, adaptation to triclosan by S. aureus appears to involve multiple genetic pathways. BioMed Central 2013-07-30 /pmc/articles/PMC3733935/ /pubmed/23898801 http://dx.doi.org/10.1186/1471-2180-13-177 Text en Copyright © 2013 Nielsen et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Article
Nielsen, Lene Nørby
Larsen, Marianne Halberg
Skovgaard, Sissel
Kastbjerg, Vicky
Westh, Henrik
Gram, Lone
Ingmer, Hanne
Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency
title Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency
title_full Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency
title_fullStr Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency
title_full_unstemmed Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency
title_short Staphylococcus aureus but not Listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabI expression and agr deficiency
title_sort staphylococcus aureus but not listeria monocytogenes adapt to triclosan and adaptation correlates with increased fabi expression and agr deficiency
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3733935/
https://www.ncbi.nlm.nih.gov/pubmed/23898801
http://dx.doi.org/10.1186/1471-2180-13-177
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