The role of adherence of Haemophilus influenzae to epithelial surfaces in the pathogenesis of infection is unknown. Fluorescent-antibody and radiolabeled adherence methods were adapted to study H. influenzae adherence to human buccal epithelial cells. By the fluorescent-antibody method, 19 of 21 (90%) nontypable H. influenzae strains were found to be adherent compared with 2 of 42 (5%) type b strains (P < 0.0001). Using a radiolabeled adherence method, we found that 9 of 12 (75%) nontypable H. influenzae strains were adherent to buccal epithelial cells whereas only 3 of 32 (9%) type b strains were adherent (P = 0.001). Results of H. influenzae adherence examined by both methods correlated significantly (P = 0.01). H. influenzae adherence to adult pharyngeal, nasal, and buccal epithelial cells was comparable. Type b H. influenzae did not adhere to the buccal epithelial cells of well children, children with H. influenzae type b disease, or children with upper respiratory infections. In contrast, nontypable H. influenzae did adhere to the buccal epithelial cells of well children and children with upper respiratory infections. These observed in vitro differences in adherence between nontypable and type b H. influenzae strains may explain differences in colonization, pathogenesis, and types of infection due to nontypable and type b H. influenzae.Bacterial adherence to the surface of epithelial cells plays an important role in the colonization and pathogenicity of numerous bacterial species (1,2,9,11,15,16). Little information is available about Haemophilus influenzae adherence to epithelial cells despite the fact that among pediatric patients type b causes serious infections, such as meningitis, epiglottitis, septicemia, pneumonia, septic arthritis, and cellulitis; nontypable H. influenzae commonly causes less serious infections, such as otitis media and conjunctivitis.We examined the adherence characteristics of H. influenzae type b and nontypable H. influenzae strains to buccal epithelial cells (BEC) from healthy adults and children, as well as sick children, by fluorescent-antibody (FA) and radioisotope-labeled methods.
MATERIALS AND METHODSBEC. Human BEC were obtained by scraping buccal mucosa from healthy adult male and female laboratory personnel with a wooden tongue blade which was then immersed in 10 ml of cold Dulbecco's phosphatebuffered saline (PBS), pH 7.2 (GIBCO Laboratories, Grand Island, N.Y.), and agitated for 30 s on a Vortex mixer. The BEC were washed with PBS over a 12-,um (pore size) polycarbonate membrane filter (Nuclepore Corp., Pleasanton, Calif.) in a filter manifold (Milli-pore Corp., Bedford, Mass.) and were harvested by suspending the ifiter in 10 ml of PBS and agitating on a Vortex mixer. BEC were counted with a hemacytometer, and the volume was adjusted to yield 2 x 104 to 8 x 104 BEC/ml of PBS.H. influenzae strains. The H. influenzae strains were clinical isolates from patients at Texas Children's Hospital and Ben Taub General Hospital in Houston, Tex. The strains were serotyped (14) and ...
