To release sialic acids for use as carbon and energy sources for this non-pathogenic bacterium while in pathogenic microorganisms, sialidases have been suggested to be pathogenic factors. Hydrolysis of alpha-(2->3)-, alpha-(2->6)-, alpha-(2->8)- glycosidic linkages of terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates. By N-acetylneuraminic acid, colominic acid, and sialic acid. Belongs to the glycosyl hydrolase 33 family.