A 10-μg/mL solution of lipopolysaccharide derived from Klebsiella pneumoniae was inoculated into the middle ears of guinea pigs. The animals were killed painlessly on the first, third, or seventh day after inoculation, and the mucosal samples from the bony portion of the eustachian tube were examined for ciliary activity and epithelial morphology. On the first and third days, when middle ear effusions were present, deterioration of ciliary activity and morphologic changes in the mucociliary system were observed. On the seventh day, when middle ear effusions were absent, the ciliary activity had recovered to normal. Our data show that endotoxin extracted from K pneumoniae can produce otitis media with effusion and that dysfunction of cilia caused by endotoxin is a factor responsible for the manifestation of otitis media.
