Lectin mediated adhesion of Streptococcus pneumoniae and its specific inhibition in vitro and in vivo.

According to our hypothesis, bacterial lectins play an important role in the organotropy of infectious diseases which is analogous to the metastasis of tumor cells. As a model for proving this, we investigated the specific lectin of Streptococcus pneumoniae, which has N-acetyl-D-glucosamine/D-galactose (GlcNAc-Gal) specificity. In vitro, after incubation with Streptococcus pneumoniae, cryotome sections of various organs from Balb/c-mice showed remarkable quantitative differences of bacterial adhesion to the organ cells. Whereas lungs and meninges were closely settled with bacteria, attachment to other organs (e.g. liver, spleen, brain) was lacking. In vitro lectin-blocking by GlcNAc completely prevented the adherence of Streptococcus pneumoniae to lungs and meninges. Other non-related carbohydrates (e.g. D-mannose, D-xylose) showed no effect. During in vivo experiments with Balb/c-mice, intratracheal application of Streptococcus pneumoniae led to a diffuse settlement of the lung. However, bacterial lectin-blocking with intratracheal GlcNAc administration completely inhibited adhesion to the organ cells of the lung. Therefore blocking of bacterial adhesins with competitive specific monosaccharides can completely prevent bacterial adhesion processes, a fact, which opens therapeutical aspects.