An extracellular Staphylococcus epidermidis polysaccharide: relation to Polysaccharide Intercellular Adhesin and its implication in phagocytosis.
BMC Microbiol
; 12: 76, 2012 May 17.
Article
en En
| MEDLINE
| ID: mdl-22594478
ABSTRACT
BACKGROUND:
The skin commensal and opportunistic pathogen Staphylococcus epidermidis is a leading cause of hospital-acquired and biomaterial-associated infections. The polysaccharide intercellular adhesin (PIA), a homoglycan composed of ß-1,6-linked N-acetylglucosamine residues, synthesized by enzymes encoded in icaADBC is a major functional factor in biofilm accumulation, promoting virulence in experimental biomaterial-associated S. epidermidis infection. Extracellular mucous layer extracts of S. epidermidis contain another major polysaccharide, referred to as 20-kDa polysaccharide (20-kDaPS), composed mainly out of glucose, N-acetylglucosamine, and being partially sulfated. 20-kDaPS antiserum prevents adhesion of S. epidermidis on endothelial cells and development of experimental keratitis in rabbits. Here we provide experimental evidence that 20-kDaPS and PIA represent distinct molecules and that 20-kDaPS is implicated in endocytosis of S. epidermidis bacterial cells by human monocyte-derived macrophages.RESULTS:
Analysis of 75 clinical coagulase-negative staphylococci from blood-cultures and central venous catheter tips indicated that 20-kDaPS is expressed exclusively in S. epidermidis but not in other coagulase-negative staphylococcal species. Tn917-insertion in various locations in icaADBC in mutants M10, M22, M23, and M24 of S. epidermidis 1457 are abolished for PIA synthesis, while 20-kDaPS expression appears unaltered as compared to wild-type strains using specific anti-PIA and anti-20-kDaPS antisera. While periodate oxidation and dispersin B treatments abolish immuno-reactivity and intercellular adhesive properties of PIA, no abrogative activity is exerted towards 20-kDaPS immunochemical reactivity following these treatments. PIA polysaccharide I-containing fractions eluting from Q-Sepharose were devoid of detectable 20-kDaPS using specific ELISA. Preincubation of non-20-kDaPS-producing clinical strain with increasing amounts of 20-kDaPS inhibits endocytosis by human macrophages, whereas, preincubation of 20-kDaPS-producing strain ATCC35983 with 20-kDaPS antiserum enhances bacterial endocytosis by human macrophages.CONCLUSIONS:
In conclusion, icaADBC is not involved in 20-kDaPS synthesis, while the chemical and chromatographic properties of PIA and 20-kDaPS are distinct. 20-kDaPS exhibits anti-phagocytic properties, whereas, 20-kDaPS antiserum may have a beneficial effect on combating infection by 20-kDaPS-producing S. epidermidis.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Fagocitosis
/
Polisacáridos Bacterianos
/
Staphylococcus epidermidis
/
Macrófagos
Límite:
Humans
Idioma:
En
Revista:
BMC Microbiol
Asunto de la revista:
MICROBIOLOGIA
Año:
2012
Tipo del documento:
Article
País de afiliación:
Grecia