Detection of endotoxin in ear specimens from patients with chronic otitis media by means of the limulus amebocyte lysate test.

The limulus amebocyte lysate (LAL) test is the most sensitive procedure for the detection of endotoxic lipopolysaccharides. The test was applied to middle ear fluids, cholesteatomas, and granulation tissue specimens from 31 patients in parallel with bacteriologic examination. The LAL test and bacteriologic examination yielded concordant results with 26 out of 28 specimens. A positive LAL test was obtained with 11 specimens containing endotoxin-producing organisms. The test became positive within 60 min of incubation in 10 out of 11 specimens and in 1 specimen between 1 and 24 h, suggesting that, in the majority of specimens, endotoxin was present in the specimen itself and that the result was not due to the in vitro multiplication of the microorganisms. All negative tests remained negative for 24 h. It is conceivable that endotoxin present in ear fluids may contribute to the pathologic changes in chronic otitis media.