Pneumococci with capsules. Micrograph of Gram-stained Streptococcus pneumoniae bacteria in sputum. Capsules around Streptococcus pneumoniae cells. Pneumococcus with a capsule in sputum. Encapsulated S.pneumoniae bacteria, morphology and arrangement of S.pneumoniae bacterial cells.

streptococcus pneumoniae with a polysaccharide capsule

Pneumococci in sputum surrounded by a wide layer of a polysaccharide capsule. Polysaccharide capsule in pneumococci is considered to be the main factor of virulence as it effectively hinders leucocytes in phagocytosis. Gram stain, magnification ×1000.