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Search for the insertion element IS256 within the ica locus of Staphylococcus epidermidis clinical isolates collected from biomaterial-associated infections

Paper ID Volume ID Publish Year Pages File Format Full-Text
12917 822 2004 9 PDF Available
Title
Search for the insertion element IS256 within the ica locus of Staphylococcus epidermidis clinical isolates collected from biomaterial-associated infections
Abstract

Staphylococcus epidermidis biofilm-forming strains produce a polysaccharide intercellular adhesin (PIA), which mediates bacterial cell aggregation and favours the colonisation on prosthetic implants. PIA synthesis is regulated by the icaADBC locus. In vitro, by repeated subcultures of a biofilm-producing strain, the loss of the ability to produce biofilm appears associated with the insertion of the IS256 element into the ica locus. This study was aimed (i) to investigate if the five genes of ica locus are always all present in different strains of S. epidermidis, and (ii) to search if IS256 insertion naturally occurs in ica locus without making recourse to the experimental procedure of repeated subcultures of strains. 120 S. epidermidis clinical isolates from peri-prosthesis infections were investigated both by an original multiplex PCR analysis of the ica genes and by PCR amplification of the IS256 element. Also two reference strains (the biofilm-negative S. epidermidis ATCC 12228 and the biofilm-forming ATCC 35984 [RP62A]) and two biofilm-negative RP62A-derived acriflavin mutants (D9 and HAM892) were analysed. D9 e HAM892 were for the first time shown to contain in ica locus, at the base 3319, a 1300-bp insertion with a DNA sequence corresponding to IS256. Among the 120 clinical isolates, 51 (43%) turned out completely ica-positive, 69 completely ica-negative (57%).The genes of the ica locus appear, in all cases of the present collection, strictly linked each other, so they are either all present or all absent.In this collection, IS256 was present in eight out of the 69 ica-negative strains and in 34 out of the 51 ica-positive strains. IS256, also when present in bacterial genomic DNA, was never found inside the ica locus, thus suggesting that insertion/excision of this element is not a natural occurring mechanism for off/on switching of biofilm production.

Keywords
Staphylococcus epidermidis; Biomaterial-associated infections; Biofilm; ica locus; IS256; Polysaccharide intercellular adhesin
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Search for the insertion element IS256 within the ica locus of Staphylococcus epidermidis clinical isolates collected from biomaterial-associated infections
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 25, Issue 18, August 2004, Pages 4117–4125
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us