ELISA to determine immunoreactive Pseudomonas aeruginosa elastase in chronic suppurative otitis media

A sensitive sandwich ELISA has been developed to measure the levels of Pseudomonas aeruginosa elastase (PE) in ear discharges from chronic suppurative otitis media (CSOM) patients. Preincubation of the sample with EDTA-2Na before ELISA was employed to inhibit PE activity which hydrolyzes the anti-PE IgG antibody into a smaller molecular form. The PE levels of 10 middle ear effusions (MEE) from chronic otitis media with effusion were also measured. In CSOM, 9 of 10 samples had significant PE levels, ranging from 6.8 to 62.1 micrograms/ml, which were significantly higher than those in MEE (p less than 0.01), the majority of which was below the detection limit. Two samples of CSOM with the P. aeruginosa infection showed high PE levels. This sandwich ELISA for the measurement of PE is a very sensitive method requiring only a small sample amount.