McKenney D, Hübner J, Muller E, Wang Y, Goldmann D A, Pier G B
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115-5899, USA.
Infect Immun. 1998 Oct;66(10):4711-20. doi: 10.1128/IAI.66.10.4711-4720.1998.
Clinical isolates of coagulase-negative staphylococci often elaborate a biofilm involved in adherence to medical devices and resistance to host defenses. The biofilm contains the capsular polysaccharide/adhesin (PS/A), which mediates cell adherence to biomaterials, and another antigen, termed polysaccharide intercellular adhesin (PIA), which is thought to mediate bacterial accumulation into cellular aggregates. PIA is a polymer of beta-1, 6-linked N-acetyl glucosamine residues with a molecular mass of <30, 000 kDa. We found that recombinant Staphylococcus carnosus and Staphylococcus aureus carrying a plasmid with genes of the ica locus, which was reported to encode the biosynthetic proteins for production of PIA, were also able to synthesize PS/A. PS/A and a chemically and immunologically identical polysaccharide isolated from S. carnosus carrying the ica genes on plasmid pCN27 were found to be high-molecular-mass (>250,000 kDa), acid-stable polymers of beta-1,6-linked glucosamine substituted on the amino group primarily with succinate, although some preparations also contained acetate. Moreover, all recombinant staphylococcal strains with the ica genes had the biologic properties previously attributed to PS/A. ica-positive strains readily formed an in vitro biofilm on plastic, adhered 3- to 10-fold more to catheters during a 30-min assay compared with control strains carrying only the cloning vector, adsorbed out antibodies to PS/A from immune serum, and elaborated a capsule visualized by immunoelectron microscopy with antisera to PS/A. These properties were also seen with PS/A-producing strains of Staphylococcus epidermidis, but not with transposon mutants lacking PS/A. An antiserum raised to PIA contained high-titer antibody to PS/A that was readily adsorbed out by PS/A-positive strains of S. epidermidis and recombinant strains of staphylococci carrying the ica genes. We conclude that the ica locus encodes production of PS/A and that the properties of S. epidermidis associated with initial bacterial adherence, biofilm formation, and intercellular adhesion can be correlated with elaboration of PS/A.
凝固酶阴性葡萄球菌的临床分离株通常会形成一种生物膜，该生物膜参与细菌对医疗器械的黏附以及对宿主防御的抵抗。这种生物膜含有介导细胞黏附于生物材料的荚膜多糖/黏附素（PS/A），以及另一种抗原，称为多糖细胞间黏附素（PIA），据认为它介导细菌聚集成细胞聚集体。PIA是一种由β-1,6-连接的N-乙酰葡糖胺残基组成的聚合物，分子量<30,000 kDa。我们发现，携带据报道编码PIA生物合成蛋白的ica基因座基因的重组肉葡萄球菌和金黄色葡萄球菌也能够合成PS/A。从携带质粒pCN27上ica基因的肉葡萄球菌中分离出的PS/A以及一种化学和免疫学上相同的多糖被发现是高分子量（>250,000 kDa）、酸稳定的β-1,6-连接葡糖胺聚合物，其氨基主要被琥珀酸取代，尽管一些制剂也含有乙酸盐。此外，所有携带ica基因的重组葡萄球菌菌株都具有先前归因于PS/A的生物学特性。ica阳性菌株很容易在塑料上形成体外生物膜，在30分钟的试验中与仅携带克隆载体的对照菌株相比，对导管的黏附力高3至10倍，从免疫血清中吸附出针对PS/A的抗体，并通过用针对PS/A的抗血清进行免疫电子显微镜观察到形成了荚膜。表皮葡萄球菌产生PS/A的菌株也具有这些特性，但缺乏PS/A的转座子突变体则没有。针对PIA产生的抗血清含有高滴度的针对PS/A的抗体，该抗体很容易被表皮葡萄球菌PS/A阳性菌株和携带ica基因的葡萄球菌重组菌株吸附。我们得出结论，ica基因座编码PS/A的产生，并且表皮葡萄球菌与细菌初始黏附、生物膜形成和细胞间黏附相关的特性可能与PS/A的产生有关。
