USE OF SEROLOGY TO DIAGNOSE PNEUMONIA CAUSED BY NONENCAPSULATED HAEMOPHILUS-INFLUENZAE AND MORAXELLA-CATARRHALIS

Antibodies against nonencapsulated Haemophilus influenzae and Moraxell a (Branhamella) catarrhalis were measured by ELISA in paired sera from 158 adult patients with pneumonia. A mixture of 10 clinical isolates of each species was used as antigen. Eleven patients (7%) showed signi ficant increases in antibody to H. influenzae. In 3 of them, the organ ism was isolated from transtracheal aspirate and in another 7 from spu tum, nasopharynx, or both. Six patients with nonencapsulated H. influe nzae in transtracheal aspirate cultures did not show any antibody incr ease. Six patients had significant increases in antibody to M. catarrh alis. The organism was isolated in transtracheal aspirates from 1 of t hem and in sputum and nasopharynx (or both) from another 3. Two patien ts with M. catarrhalis in transtracheal aspirate cultures showed no an tibody response. In conclusion, the serologic methods increased the po ssibility to diagnose infections caused by the two agents but had low sensitivity.