Human antibody response to Moraxella catarrhalis antigens

Moraxella catarrhalis was isolated from 68 of 200 (34%) sputum and 56 (28%) nasopharyngeal swab samples of patients with community-acquired pneumonia. Of the 68 pneumonia patients, 42 (61.8%) were males and 26 (38.2%) females. Fifty one of the 68 patients (75%) had chronic underlying diseases. beta-lactamase was produced by 37 (54.4%) of the 68 sputum samples and 32(57.1%) of the 56 nasopharyngeal isolates. In an ELISA using outer membrane protein antigens of M. catarrhalis against patient sera showed 40 of 68 (58.8%), and 43 of 68 (63.2%) significant increase in convalescent to acute sera when IgA, IgM and IgG3 were used respectively. In control sera only of 30(3.3%) and none showed significant antibody rise when IgA, IgM and IgG3 conjugates were used respectively (P < 0.05).