Document Detail

Morphological and biochemical changes in Pseudomonas fluorescens biofilms induced by sub-inhibitory exposure to antimicrobial agents.
MedLine Citation:
PMID:  19295649     Owner:  NLM     Status:  MEDLINE    
Confocal laser scanning microscopy (CLSM) and scanning transmission X-ray microscopy (STXM) were used to examine the morphological and biochemical changes in Pseudomonas fluorescens biofilms grown in the presence of subinhibitory concentrations of 4 antimicrobial agents: triclosan, benzalkonium chloride, chlorhexidine dihydrochloride, and trisodium phosphate. CLSM analyses using the stains SYTO9 and propidium iodide indicated that the antimicrobial agents affected cell membrane integrity and cellular density to differing degrees. However, fluorescein diacetate assays and plate counts demonstrated that the cells remained metabolically active. Fluorescent lectin binding assays showed that changes in the arrangement and composition of the exopolymer matrix of the biofilms also occurred and that these changes depended on the antimicrobial agent. Detailed single cell analyses using STXM provided evidence that the cell morphology, and the spatial distribution and relative amounts of protein, lipids and polysaccharides in the biofilms and within the cells were different for each antimicrobial. The distribution of chlorhexidine in the biofilm, determined from its distinct spectral signature, was localized mainly inside the bacterial cells. Each antimicrobial agent elicited a unique response; P. fluorescens cells and biofilms changed their morphology and architecture, as well as the distribution and abundance of biomacromolecules, in particular the exopolymer matrix. Pseudomonas fluorescens also exhibited adaptation to benzalkonium chloride at 10 microg/mL. Our observations point to the importance of changes in the quantity and chemistry of the exopolymeric matrix in the response to antimicrobial agents and suggest their importance as targets for control.
James J Dynes; John R Lawrence; Darren R Korber; George D W Swerhone; Gary G Leppard; Adam P Hitchcock
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Canadian journal of microbiology     Volume:  55     ISSN:  0008-4166     ISO Abbreviation:  Can. J. Microbiol.     Publication Date:  2009 Feb 
Date Detail:
Created Date:  2009-03-19     Completed Date:  2009-07-09     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372707     Medline TA:  Can J Microbiol     Country:  Canada    
Other Details:
Languages:  eng     Pagination:  163-78     Citation Subset:  IM    
Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON-L8S-4M1, Canada.
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MeSH Terms
Anti-Infective Agents / pharmacology*
Bacterial Proteins / metabolism
Biofilms / drug effects*
Lipid Metabolism
Microbial Viability / drug effects
Microscopy, Confocal
Microscopy, Electron, Scanning
Polysaccharides, Bacterial / metabolism
Pseudomonas fluorescens / cytology*,  drug effects*,  physiology
Reg. No./Substance:
0/Anti-Infective Agents; 0/Bacterial Proteins; 0/Polysaccharides, Bacterial

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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