Buret A, Ward K H, Olson M E, Costerton J W
Department of Biological Sciences, University of Calgary, Alberta, Canada.
J Biomed Mater Res. 1991 Jul;25(7):865-74. doi: 10.1002/jbm.820250706.
This study examines the morphology, ultrastructure, and microbiology of the intact biofilm developing on an implant surface. Silastic subdermal implant material was colonized with P. aeruginosa and surgically inserted into the peritoneal cavity of adult rabbits. After 4, 8, 28, and 42 days implants were recovered and the intact biofilms examined. P. aeruginosa colonized the implant throughout the entire experimental time. Microcolonies of glycocalyx-coated bacteria were observed within the biofilm. However, the bulk of the biofilm was host-generated and typically contained phagocytes trapped within a thick mesh of fibrin. Polymorphonuclear neutrophils were the predominant cell type. Isolated erythrocytes, macrophages, and fibroblasts were also observed. By day 28, the biofilm was enclosed in a fibrous capsule of vascularized connective tissue. The low numbers of neutrophils seen in biofilms from sterile Silastic sheets implanted into control animals suggested that neutrophilia may represent a specific cellular response to the bacterial colonization. The results indicate that the cell-mediated immune response provides for most of the biofilm mass on colonized implant surfaces. Inactivated phagocytes trapped in fibrin may "wall-off" the embedded bacterial microcolonies and thus shield them from live phagocytic leucocytes. Such a mechanism may play an important role in the pathogenesis of prosthetic device infections.
本研究检测了在植入物表面形成的完整生物膜的形态学、超微结构和微生物学特征。将硅橡胶皮下植入材料接种铜绿假单胞菌后，通过手术植入成年兔的腹腔。在4天、8天、28天和42天后取出植入物，对完整的生物膜进行检测。在整个实验期间，铜绿假单胞菌均定植于植入物上。在生物膜内观察到了被糖萼包裹的细菌微菌落。然而，生物膜的主体是由宿主产生的，通常含有被困在厚厚的纤维蛋白网中的吞噬细胞。多形核中性粒细胞是主要的细胞类型。还观察到了单个的红细胞、巨噬细胞和成纤维细胞。到第28天，生物膜被血管化结缔组织的纤维囊包裹。植入无菌硅橡胶片的对照动物的生物膜中可见少量中性粒细胞，这表明中性粒细胞增多可能代表对细菌定植的一种特异性细胞反应。结果表明，细胞介导的免疫反应构成了定植植入物表面生物膜的大部分。被困在纤维蛋白中的失活吞噬细胞可能会“隔离”嵌入的细菌微菌落，从而使其免受活的吞噬性白细胞的攻击。这种机制可能在假体装置感染的发病机制中起重要作用。
