The role of sigmaB in persistence of Staphylococcus epidermidis foreign body infection

TY - JOUR

T1 - The role of sigmaB in persistence of Staphylococcus epidermidis foreign body infection

AU - Pintens, Valerie

AU - Massonet, Caroline

AU - Merckx, Rita

AU - Vandecasteele, Stefaan

AU - Peetermans, Willy E

AU - Knobloch, Johannes K-M

AU - Van Eldere, Johan

PY - 2008/9

Y1 - 2008/9

N2 - Staphylococcal biofilm formation depends on the transcription factor sigma(B). We further investigated the role of sigma(B) in biofilm formation and persistence in vitro and in vivo in a subcutaneous rat model. As expected, expression of all sigma(B) operon genes was transiently higher in the first 6 h of biofilm formation compared to planktonic bacteria, concurrent with a temporary upregulation of icaA and aap expression. However, we also observed a second upregulation of sigB expression in biofilm more than 2 days old without upregulation of icaA or aap. Biofilm formation by Staphylococcus epidermidis strains 8400 and 1457 was compared to that of isogenic mutants with inactivation of rsbU, of rsbUVW and of the entire sigma(B) operon. Both wild-type strains and the constitutively sigB-expressing rsbUVW mutant showed a strong biofilm-positive phenotype. The rsbUVW mutant biofilm was, however, thinner and more evenly spread than the wild-type biofilm. Inactivation of SigB in the rsbUVWsigB mutant or mutation of the positive regulator RsbU reduced both the number of sessile bacteria and polysaccharide intercellular adhesin (PIA) synthesis. These differences between the wild-types and their respective mutants appeared after 6 h in in vitro biofilms but only after 4 days in in vivo biofilms. Our results provide additional evidence for a role for sigma(B) in biofilm formation. They also suggest a role for sigma(B) in biofilm maturation and stability that is independent of PIA or accumulation-associated protein (Aap) and point to significant differences in the temporal development between in vitro and in vivo biofilms.

AB - Staphylococcal biofilm formation depends on the transcription factor sigma(B). We further investigated the role of sigma(B) in biofilm formation and persistence in vitro and in vivo in a subcutaneous rat model. As expected, expression of all sigma(B) operon genes was transiently higher in the first 6 h of biofilm formation compared to planktonic bacteria, concurrent with a temporary upregulation of icaA and aap expression. However, we also observed a second upregulation of sigB expression in biofilm more than 2 days old without upregulation of icaA or aap. Biofilm formation by Staphylococcus epidermidis strains 8400 and 1457 was compared to that of isogenic mutants with inactivation of rsbU, of rsbUVW and of the entire sigma(B) operon. Both wild-type strains and the constitutively sigB-expressing rsbUVW mutant showed a strong biofilm-positive phenotype. The rsbUVW mutant biofilm was, however, thinner and more evenly spread than the wild-type biofilm. Inactivation of SigB in the rsbUVWsigB mutant or mutation of the positive regulator RsbU reduced both the number of sessile bacteria and polysaccharide intercellular adhesin (PIA) synthesis. These differences between the wild-types and their respective mutants appeared after 6 h in in vitro biofilms but only after 4 days in in vivo biofilms. Our results provide additional evidence for a role for sigma(B) in biofilm formation. They also suggest a role for sigma(B) in biofilm maturation and stability that is independent of PIA or accumulation-associated protein (Aap) and point to significant differences in the temporal development between in vitro and in vivo biofilms.

KW - Analysis of Variance

KW - Animals

KW - Bacterial Proteins/genetics

KW - Biofilms/growth & development

KW - Catheters, Indwelling/microbiology

KW - DNA, Bacterial/genetics

KW - Foreign-Body Reaction/microbiology

KW - Gene Expression Regulation, Bacterial

KW - Microscopy, Confocal

KW - Microscopy, Electron, Scanning

KW - Mutation

KW - Operon

KW - Phenotype

KW - Polysaccharides, Bacterial/biosynthesis

KW - RNA, Bacterial/genetics

KW - Rats

KW - Rats, Inbred F344

KW - Reverse Transcriptase Polymerase Chain Reaction

KW - Sigma Factor/genetics

KW - Staphylococcal Infections/microbiology

KW - Staphylococcus epidermidis/genetics

KW - Time Factors

KW - Up-Regulation

U2 - 10.1099/mic.0.2007/015768-0

DO - 10.1099/mic.0.2007/015768-0

M3 - SCORING: Journal article

C2 - 18757816

VL - 154

SP - 2827

EP - 2836

JO - MICROBIOL-SGM

JF - MICROBIOL-SGM

SN - 1350-0872

IS - Pt 9

ER -