Evidence for N-acetylmannosamine as an ocular receptor for P. aeruginosa adherence to scarified cornea.

This study provides evidence for an N-acetylmannosamine (manNac) receptor mediating in vivo bacterial adherence of P. aeruginosa to the scarified corneal epithelial surface. Bacteria, whether exposed to the inhibiting sugar or not, did not adhere immediately after inoculation, but required time in contact with the scarified corneal surface to adhere and adherence increased with time. Organisms were observed primarily adherent to the surface of epithelial cells lining the wound and were less frequently seen on areas of denuded stroma. Saturation of binding sites on the bacterial surface by manNac inhibited attachment of the organisms to newly exposed surface membrane receptors. In vivo protection studies showed excellent correlation with quantitative analysis of scanning electron micrographs, in that the number of adherent organisms at the corneal surface at 60 min following scarification and bacterial inoculation was decreased significantly by prior treatment of the bacteria with manNac when compared with PBS or the other monosaccharides. These data were confirmed by quantitative bacterial culture of excised corneas which had been similarly infected in vivo with PBS or manNac treated organisms.