Experimental Alteration of Chinchilla Middle Ear Mucosae by Bacterial Neuraminidase

Streptococcus pneumoniae secretes a variety of extracellular glycosidases including a neuraminidase which has been found in middle ear effusion from patients with both acute and chronic otitis media. This enzyme cleaves sialic acid from membrane glycoproteins, thereby exposing galactose residues, the penultimate sugar. The ability of partially purified neuraminidase to alter the middle ear mucosa was investigated in the chinchilla. After incubation with neuraminidase, chinchilla middle ears were removed and exposed to galactose residues labeled with tritium. Membrane glycoproteins were solubilized and separated according to molecular weight by sodium dodecylsulfate electrophoresis. Increases in tritium incorporation, when compared to control incubations, indicated that galactose residues had been exposed and sialic acid residues removed from glycoproteins of both high and low molecular weight. Such membrane destruction could contribute significantly to the pathology of otitis media with effusion.