Open Accessagr ‐Genotyping and transcriptional analysis of biofilm‐producing Staphylococcus aureus
Author(s) -
Cafiso Viviana,
Bertuccio Taschia,
Santagati Maria,
Demelio Vanessa,
Spina Daniela,
Nicoletti Giuseppe,
Stefani Stefania
Publication year - 2007
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1111/j.1574-695x.2007.00298.x
Subject(s) - biofilm , biology , microbiology and biotechnology , operon , genotype , genotyping , locus (genetics) , gene , sigma factor , typing , transcription (linguistics) , promoter , genetics , gene expression , bacteria , escherichia coli , linguistics , philosophy
We investigated the correlation between biofilm production and the accessory‐gene‐regulator ( agr ) in 29 strains isolated from catheter‐associated infections compared to a control group (30 isolates). All strains were tested for their ability to produce biofilm in a static system, and their agr genotype was determined. ScaI‐restriction fragment length polymorphism for agr ‐typing showed that strong biofilm‐producing strains belong to agr ‐ type II. We found two new agr ‐variants, and sequence analysis of the three PCR products revealed the insertion of IS 256 within the agr‐ locus. Biofilm production was assessed and correlated with agr functionality, with the expression of the ica ‐operon and of two transcriptional regulators, sar A and rsb U. Our data show that agr ‐II strains produce large amounts of biofilm, possess a defective agr ‐system show early transcription of ica A and are defective in haemolysin activity, ica R transcription, and in the expression of the σ B activator rsb U. Strains with agr III are medium biofilm producers, have an inactive agr ‐system, but express ica AR and rsb U in the late‐ and postexponential growth phases. In agr I–IV‐ and ‐IA‐variants, medium or weak biofilm production was found. In these strains, the agr ‐locus was fully functional, rsb U‐ ica R and ica A were found in the late‐ and/or postexponential phases. Biofilm production was not affected by sar A.