Topo-optical investigations on the surface of bacterial cells during the phagocytosis of Klebsiella pneumoniae in mouse

Polarisation optical methods provide the means to perform sub-microscopic investigations on structures containing spatially highly ordered molecules, for example the cell envelope of prokaryotic cells. Such structures can evoke birefringence, which can be enhanced or modified by different dyes or reagents, thus providing the possibility of a more specific investigation of the composition and structure of bacterial surface compounds. Klebsiella pneumoniae synthesises sterically different carbohydrate-rich structures, including those of the outermost capsular polysaccharide, the polysaccharide somatic antigen of the lipopolysaccharide molecule and the peptidoglycan layer of the cell wall. In the study reported here, the nature and intensity of topo-optical activity of these structures was analysed using the aldehyde-bisulphite-toluidine blue reaction, sialic acid topo-optical reactions and chlorpromazine-eosin charge transfer reactions. Furthermore, a mouse intraperitoneal model was used to analyse alterations in topo-optical characteristics of bacteria during phagocytosis. Both encapsulated and non-encapsulated bacterial cells changed their original pattern and orientation of birefringence after being phagocytosed.