Evaluation of countercurrent immunoelectrophoresis as a diagnostic tool in bacterial otitis media

The diagnostic efficiency of countercurrent immunoelectrophoresis (CIE) and correlation of clinical and bacteriological data were studied in 184 middle ear effusions (MEE) from 125 patients diagnosed as acute primary, acute recurrent otitis media, and chronic MEE. Significant differences between stage of otitis media (OM), patient age and type of MEE were found. Streptococcus pneumoniae was isolated in 22% of the overall MEE, 26% in the acute primary and 26% in acute recurrent OM. Among the S. pneumoniae isolates, 82.5% were detected by CIE and culture, 15% only by culture and 2.5% only by CIE. Most S. pneumoniae isolates identified by culture and CIE were in a purulent MEE (64%) while those identified by culture only were in a mucoid MEE (67%). Haemophilus influenzae overall incidence was 29%; 13% of them produced beta-lactamase and only 4% were serotype b. The H. influenzae serotype b strains were detected by culture as well as CIE, so the overall effectiveness of CIE for S. pneumoniae and H. influenzae serotype b was 19.5% and 22 to 23% for acute primary and recurrent OM. Sterile cultures were obtained in 37.5% of the overall MEE. The CIE seems to be a useful screening test, culture remaining the method for definitive bacterial identification in MEE.