title: agr-Genotyping and transcriptional analysis of biofilm-producing Staphylococcus aureus.
abstract: 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 IS256 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, sarA and rsbU. Our data show that agr-II strains produce large amounts of biofilm, possess a defective agr-system show early transcription of icaA and are defective in haemolysin activity, icaR transcription, and in the expression of the sigma(B) activator rsbU. Strains with agrIII are medium biofilm producers, have an inactive agr-system, but express icaAR and rsbU in the late- and postexponential growth phases. In agrI-IV- and -IA-variants, medium or weak biofilm production was found. In these strains, the agr-locus was fully functional, rsbU-icaR and icaA were found in the late- and/or postexponential phases. Biofilm production was not affected by sarA.
authors.affiliation: Department of Microbiology, University of Catania, Catania, Italy.
authors.forename: Viviana
authors.initials: V
authors.lastname: Cafiso
authors.forename: Taschia
authors.initials: T
authors.lastname: Bertuccio
authors.forename: Maria
authors.initials: M
authors.lastname: Santagati
authors.forename: Vanessa
authors.initials: V
authors.lastname: Demelio
authors.forename: Daniela
authors.initials: D
authors.lastname: Spina
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Nicoletti
authors.forename: Stefania
authors.initials: S
authors.lastname: Stefani
mesh_terms: D001426:Bacterial Proteins / Q000145:classification* / Q000235:genetics / Q000502:physiology; D018441:Biofilms / Q000254:growth & development*; D005838:Genotype; D012808:Sigma Factor / Q000502:physiology; D013211:Staphylococcus aureus / Q000235:genetics* / Q000502:physiology*; D015534:Trans-Activators / Q000145:classification* / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D015534:Trans-Activators