Preliminary Serologic Evidence for a Pathogenic Role of Branhamella catarrhalis

Branhamella catarrhalis has been suspected, on the basis of bacteriologic culture results, to have a pathogenic role in 60%–9% of cases of acute otitis media as well as in other upper respiratory tract infections. Serologic evidence of this role was obtained with use of an enzyme immunoassay to detect antibodies to B. catarrhalis. The presence of both IgG and IgA antibodies to Branhamella in the serum and/or middle ear fluid (MEF) of children with acute otitis media correlated with the isolation of B. catarrhalis from cultures of their MEF. An increase in titer of antibodies to Branhamella between acutephase and convalescent-phase serum samples was found in 10 of the 19 children with otitis media from whom B. catarrhalis but no other pathogen was isolated from the MEF. Such an increase was found in none of the 14children with otitis media caused by other organisms.