SELECTIVE ADHERENCE OF NONTYPABLE HAEMOPHILUS-INFLUENZAE (NTHI) TO MUCUS OF EPITHELIAL-CELLS IN THE CHINCHILLA EUSTACHIAN-TUBE AND MIDDLE-EAR

Frozen sections of chinchilla Eustachian tube (ET) and middle ear muco sa were incubated with either FITC-labeled non-typeable Haemophilus in fluenzae (NTHi) or Bordetella pertussis. The number of bacteria adhere nt to ''roof'' vs ''floor'' regions was compared for each of three ana tomic portions of the ET and for middle ear epithelium noting whether bacteria adhered to mucus or to epithelial cells. NTHi strains adhered significantly greater to mucus in the ET lumen whereas B. pertussis p referentially adhered to epithelial cells lining the ET (P less than o r equal to 0.05). A non-fimbriated isogenic mutant of NTHi adhered sig nificantly less to mucus than the parental isolate at all sites of the ET floor (P less than or equal to 0.05). Isolated fimbrin protein adh ered to ET mucus and blocked adherence of whole organisms. Treatment w ith the mucolytic agent N-acetyl-L-cysteine resulted in significantly reduced adherence of NTHi to mucus (P less than or equal to 0.001) and eliminated the ability to detect binding of isolated fimbrin protein. N-acetyl-L-cysteine treatment did not affect adherence of either B. p ertussis or NTHi to epithelial cells. These data indicated that NTHi m ay mediate ascension of the ET from the nasopharynx primarily via adhe rence to and growth in mucus overlying the floor region of the tubal l umen. The OMP P5-homologous fimbriae were shown to contribute to this binding. (C) 1996 Academic Press Limited