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Methicillin resistance and the biofilm phenotype in Staphylococcus aureus.

McCarthy H, Rudkin JK, Black NS, Gallagher L, O'Neill E, O'Gara JP - Front Cell Infect Microbiol (2015)

Bottom Line: These virulence factors do not function independently of each other and the biofilm phenotype expressed by clinical isolates of S. aureus is influenced by acquisition of the methicillin resistance gene mecA.Expression of high level methicillin resistance in a laboratory MSSA strain resulted in (i) repression of PIA-mediated biofilm production, (ii) down-regulation of the accessory gene regulator (Agr) system, and (iii) attenuation of virulence in murine sepsis and device infection models.Here we review the mechanisms of MSSA and MRSA biofilm production and the relationships between antibiotic resistance, biofilm and virulence gene regulation in S. aureus.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland.

ABSTRACT
Antibiotic resistance and biofilm-forming capacity contribute to the success of Staphylococcus aureus as a human pathogen in both healthcare and community settings. These virulence factors do not function independently of each other and the biofilm phenotype expressed by clinical isolates of S. aureus is influenced by acquisition of the methicillin resistance gene mecA. Methicillin-sensitive S. aureus (MSSA) strains commonly produce an icaADBC operon-encoded polysaccharide intercellular adhesin (PIA)-dependent biofilm. In contrast, the release of extracellular DNA (eDNA) and cell surface expression of a number of sortase-anchored proteins, and the major autolysin have been implicated in the biofilm phenotype of methicillin-resistant S. aureus (MRSA) isolates. Expression of high level methicillin resistance in a laboratory MSSA strain resulted in (i) repression of PIA-mediated biofilm production, (ii) down-regulation of the accessory gene regulator (Agr) system, and (iii) attenuation of virulence in murine sepsis and device infection models. Here we review the mechanisms of MSSA and MRSA biofilm production and the relationships between antibiotic resistance, biofilm and virulence gene regulation in S. aureus.

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Related in: MedlinePlus

(A) Graphic representations of the biofilm phenotypes expressed by MSSA and MRSA. MSSA strains form ica-dependent, PIA-mediated biofilms whereas MRSA strains form biofilms independent of PIA and require surface proteins such as the fibronectin binding proteins, Atl-mediated cell lysis and eDNA for colonization of surfaces and biofilm accumulation. (B) Scanning electron micrographs (3500 × magnification) of biofilms formed by MSSA strain SH1000 grown in BHI media supplemented with 4% NaCl (left) and MRSA strain BH1CC grown in BHI supplemented with 1% glucose (right).
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Figure 1: (A) Graphic representations of the biofilm phenotypes expressed by MSSA and MRSA. MSSA strains form ica-dependent, PIA-mediated biofilms whereas MRSA strains form biofilms independent of PIA and require surface proteins such as the fibronectin binding proteins, Atl-mediated cell lysis and eDNA for colonization of surfaces and biofilm accumulation. (B) Scanning electron micrographs (3500 × magnification) of biofilms formed by MSSA strain SH1000 grown in BHI media supplemented with 4% NaCl (left) and MRSA strain BH1CC grown in BHI supplemented with 1% glucose (right).

Mentions: A study of ica-independent mechanisms of biofilm formation by S. aureus revealed that altered levels of autolysis were associated with defective biofilm production (Boles et al., 2010). Recently cytoplasmic proteins released during the stationary phase of growth, which may be a consequence of autolysis, have been shown to be part of the biofilm matrix of S. aureus HG003 (Foulston et al., 2014). Interestingly the release of cytoplasmic proteins during stationary phase appears to be in response to decreasing pH, which can be triggered by the addition of excess glucose to the growth media (Foulston et al., 2014) and it is worth noting that these same growth conditions promote Atl/FnBP-mediated MRSA biofilm formation (O'Neill et al., 2008). A simplified model of MSSA and MRSA biofilm mechanisms together with scanning electron micrographs of SH1000 (MSSA) and BH1CC (MRSA) biofilms is presented in Figure 1.


Methicillin resistance and the biofilm phenotype in Staphylococcus aureus.

McCarthy H, Rudkin JK, Black NS, Gallagher L, O'Neill E, O'Gara JP - Front Cell Infect Microbiol (2015)

(A) Graphic representations of the biofilm phenotypes expressed by MSSA and MRSA. MSSA strains form ica-dependent, PIA-mediated biofilms whereas MRSA strains form biofilms independent of PIA and require surface proteins such as the fibronectin binding proteins, Atl-mediated cell lysis and eDNA for colonization of surfaces and biofilm accumulation. (B) Scanning electron micrographs (3500 × magnification) of biofilms formed by MSSA strain SH1000 grown in BHI media supplemented with 4% NaCl (left) and MRSA strain BH1CC grown in BHI supplemented with 1% glucose (right).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4309206&req=5

Figure 1: (A) Graphic representations of the biofilm phenotypes expressed by MSSA and MRSA. MSSA strains form ica-dependent, PIA-mediated biofilms whereas MRSA strains form biofilms independent of PIA and require surface proteins such as the fibronectin binding proteins, Atl-mediated cell lysis and eDNA for colonization of surfaces and biofilm accumulation. (B) Scanning electron micrographs (3500 × magnification) of biofilms formed by MSSA strain SH1000 grown in BHI media supplemented with 4% NaCl (left) and MRSA strain BH1CC grown in BHI supplemented with 1% glucose (right).
Mentions: A study of ica-independent mechanisms of biofilm formation by S. aureus revealed that altered levels of autolysis were associated with defective biofilm production (Boles et al., 2010). Recently cytoplasmic proteins released during the stationary phase of growth, which may be a consequence of autolysis, have been shown to be part of the biofilm matrix of S. aureus HG003 (Foulston et al., 2014). Interestingly the release of cytoplasmic proteins during stationary phase appears to be in response to decreasing pH, which can be triggered by the addition of excess glucose to the growth media (Foulston et al., 2014) and it is worth noting that these same growth conditions promote Atl/FnBP-mediated MRSA biofilm formation (O'Neill et al., 2008). A simplified model of MSSA and MRSA biofilm mechanisms together with scanning electron micrographs of SH1000 (MSSA) and BH1CC (MRSA) biofilms is presented in Figure 1.

Bottom Line: These virulence factors do not function independently of each other and the biofilm phenotype expressed by clinical isolates of S. aureus is influenced by acquisition of the methicillin resistance gene mecA.Expression of high level methicillin resistance in a laboratory MSSA strain resulted in (i) repression of PIA-mediated biofilm production, (ii) down-regulation of the accessory gene regulator (Agr) system, and (iii) attenuation of virulence in murine sepsis and device infection models.Here we review the mechanisms of MSSA and MRSA biofilm production and the relationships between antibiotic resistance, biofilm and virulence gene regulation in S. aureus.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, School of Natural Sciences, National University of Ireland Galway, Ireland.

ABSTRACT
Antibiotic resistance and biofilm-forming capacity contribute to the success of Staphylococcus aureus as a human pathogen in both healthcare and community settings. These virulence factors do not function independently of each other and the biofilm phenotype expressed by clinical isolates of S. aureus is influenced by acquisition of the methicillin resistance gene mecA. Methicillin-sensitive S. aureus (MSSA) strains commonly produce an icaADBC operon-encoded polysaccharide intercellular adhesin (PIA)-dependent biofilm. In contrast, the release of extracellular DNA (eDNA) and cell surface expression of a number of sortase-anchored proteins, and the major autolysin have been implicated in the biofilm phenotype of methicillin-resistant S. aureus (MRSA) isolates. Expression of high level methicillin resistance in a laboratory MSSA strain resulted in (i) repression of PIA-mediated biofilm production, (ii) down-regulation of the accessory gene regulator (Agr) system, and (iii) attenuation of virulence in murine sepsis and device infection models. Here we review the mechanisms of MSSA and MRSA biofilm production and the relationships between antibiotic resistance, biofilm and virulence gene regulation in S. aureus.

Show MeSH
Related in: MedlinePlus