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Specific involvement of pilus type 2a in biofilm formation in group B Streptococcus.

Rinaudo CD, Rosini R, Galeotti CL, Berti F, Necchi F, Reguzzi V, Ghezzo C, Telford JL, Grandi G, Maione D - PLoS ONE (2010)

Bottom Line: Recently, we have characterized pili distribution and conservation in 289 GBS clinical isolates and we have shown that GBS has three pilus types, 1, 2a and 2b encoded by three corresponding pilus islands, and that each strain carries one or two islands.We also show that deletion of the major ancillary protein of type 2a did not impair biofilm formation while the inactivation of the other ancillary protein and of the backbone protein completely abolished this phenotype.Furthermore, antibodies raised against pilus components inhibited bacterial adherence to solid surfaces, offering new strategies to prevent GBS infection by targeting bacteria during their initial attachment to host epithelial cells.

View Article: PubMed Central - PubMed

Affiliation: Novartis Vaccines and Diagnostics, Siena, Italy.

ABSTRACT
Streptococcus agalactiae is the primary colonizer of the anogenital mucosa of up to 30% of healthy women and can infect newborns during delivery and cause severe sepsis and meningitis. Persistent colonization usually involves the formation of biofilm and increasing evidences indicate that in pathogenic streptococci biofilm formation is mediated by pili. Recently, we have characterized pili distribution and conservation in 289 GBS clinical isolates and we have shown that GBS has three pilus types, 1, 2a and 2b encoded by three corresponding pilus islands, and that each strain carries one or two islands. Here we have investigated the capacity of these strains to form biofilms. We have found that most of the biofilm-formers carry pilus 2a, and using insertion and deletion mutants we have confirmed that pilus type 2a, but not pilus types 1 and 2b, confers biofilm-forming phenotype. We also show that deletion of the major ancillary protein of type 2a did not impair biofilm formation while the inactivation of the other ancillary protein and of the backbone protein completely abolished this phenotype. Furthermore, antibodies raised against pilus components inhibited bacterial adherence to solid surfaces, offering new strategies to prevent GBS infection by targeting bacteria during their initial attachment to host epithelial cells.

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Related in: MedlinePlus

Influence of glucose on biofilm formation in GBS strain 515.Determination of biofilm formation by crystal violet (CV) assay of GBS strain 515 grown in THB supplemented with different glucose concentrations in 96-well polystyrene plates under static conditions at 37°C, 5% CO2 for 18 hours. Crystal violet stained, surface-attached cells were quantified by solubilizing the dye in 30% acetic acid and by measuring the absorbance at 540 nm. The mean values of three independent experiments and standard deviation are shown.
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pone-0009216-g001: Influence of glucose on biofilm formation in GBS strain 515.Determination of biofilm formation by crystal violet (CV) assay of GBS strain 515 grown in THB supplemented with different glucose concentrations in 96-well polystyrene plates under static conditions at 37°C, 5% CO2 for 18 hours. Crystal violet stained, surface-attached cells were quantified by solubilizing the dye in 30% acetic acid and by measuring the absorbance at 540 nm. The mean values of three independent experiments and standard deviation are shown.

Mentions: To assess the capacity of GBS to form biofilms, we first analyzed whether the serotype Ia strain 515 [29], expressing only pilus type 2a and previously used for pili genetic studies [22], was able to adhere to polystyrene surfaces, using the well-established biofilm assay described by O'Toole and Kolter [30]. Bacteria were grown in tissue culture plates and biofilm formation was detected by crystal violet (CV) staining, followed by dye solubilization with acetic acid. Since growth medium composition influences the capacity to form biofilm in other streptococci [31], [32], GBS strain 515 was cultured under static conditions in THB, a standard streptococcal growth medium, and in THB supplemented with increasing concentrations of glucose and biofilm formation was assessed after 18 hours of growth. While the presence or absence of glucose did not affect growth rates when bacteria were cultured in suspension (data not shown), only in the presence of glucose concentrations ≥0.4%, surface adhesion and proliferation was observed (Figure 1). Similar results were obtained using sucrose instead of glucose (data not shown).


Specific involvement of pilus type 2a in biofilm formation in group B Streptococcus.

Rinaudo CD, Rosini R, Galeotti CL, Berti F, Necchi F, Reguzzi V, Ghezzo C, Telford JL, Grandi G, Maione D - PLoS ONE (2010)

Influence of glucose on biofilm formation in GBS strain 515.Determination of biofilm formation by crystal violet (CV) assay of GBS strain 515 grown in THB supplemented with different glucose concentrations in 96-well polystyrene plates under static conditions at 37°C, 5% CO2 for 18 hours. Crystal violet stained, surface-attached cells were quantified by solubilizing the dye in 30% acetic acid and by measuring the absorbance at 540 nm. The mean values of three independent experiments and standard deviation are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2821406&req=5

pone-0009216-g001: Influence of glucose on biofilm formation in GBS strain 515.Determination of biofilm formation by crystal violet (CV) assay of GBS strain 515 grown in THB supplemented with different glucose concentrations in 96-well polystyrene plates under static conditions at 37°C, 5% CO2 for 18 hours. Crystal violet stained, surface-attached cells were quantified by solubilizing the dye in 30% acetic acid and by measuring the absorbance at 540 nm. The mean values of three independent experiments and standard deviation are shown.
Mentions: To assess the capacity of GBS to form biofilms, we first analyzed whether the serotype Ia strain 515 [29], expressing only pilus type 2a and previously used for pili genetic studies [22], was able to adhere to polystyrene surfaces, using the well-established biofilm assay described by O'Toole and Kolter [30]. Bacteria were grown in tissue culture plates and biofilm formation was detected by crystal violet (CV) staining, followed by dye solubilization with acetic acid. Since growth medium composition influences the capacity to form biofilm in other streptococci [31], [32], GBS strain 515 was cultured under static conditions in THB, a standard streptococcal growth medium, and in THB supplemented with increasing concentrations of glucose and biofilm formation was assessed after 18 hours of growth. While the presence or absence of glucose did not affect growth rates when bacteria were cultured in suspension (data not shown), only in the presence of glucose concentrations ≥0.4%, surface adhesion and proliferation was observed (Figure 1). Similar results were obtained using sucrose instead of glucose (data not shown).

Bottom Line: Recently, we have characterized pili distribution and conservation in 289 GBS clinical isolates and we have shown that GBS has three pilus types, 1, 2a and 2b encoded by three corresponding pilus islands, and that each strain carries one or two islands.We also show that deletion of the major ancillary protein of type 2a did not impair biofilm formation while the inactivation of the other ancillary protein and of the backbone protein completely abolished this phenotype.Furthermore, antibodies raised against pilus components inhibited bacterial adherence to solid surfaces, offering new strategies to prevent GBS infection by targeting bacteria during their initial attachment to host epithelial cells.

View Article: PubMed Central - PubMed

Affiliation: Novartis Vaccines and Diagnostics, Siena, Italy.

ABSTRACT
Streptococcus agalactiae is the primary colonizer of the anogenital mucosa of up to 30% of healthy women and can infect newborns during delivery and cause severe sepsis and meningitis. Persistent colonization usually involves the formation of biofilm and increasing evidences indicate that in pathogenic streptococci biofilm formation is mediated by pili. Recently, we have characterized pili distribution and conservation in 289 GBS clinical isolates and we have shown that GBS has three pilus types, 1, 2a and 2b encoded by three corresponding pilus islands, and that each strain carries one or two islands. Here we have investigated the capacity of these strains to form biofilms. We have found that most of the biofilm-formers carry pilus 2a, and using insertion and deletion mutants we have confirmed that pilus type 2a, but not pilus types 1 and 2b, confers biofilm-forming phenotype. We also show that deletion of the major ancillary protein of type 2a did not impair biofilm formation while the inactivation of the other ancillary protein and of the backbone protein completely abolished this phenotype. Furthermore, antibodies raised against pilus components inhibited bacterial adherence to solid surfaces, offering new strategies to prevent GBS infection by targeting bacteria during their initial attachment to host epithelial cells.

Show MeSH
Related in: MedlinePlus