KINETICS OF THE ASCENSION OF NTHI FROM THE NASOPHARYNX TO THE MIDDLE-EAR COINCIDENT WITH ADENOVIRUS-INDUCED COMPROMISE IN THE CHINCHILLA

To determine the kinetics of ascension of the eustachian tube (ET) by non-typeable Haemophilus influenzae (NTHi) in situ from the nasopharyn x to the middle ear using an experimental model of otitis media (OM), we examined snap-frozen sections of chinchilla ET and middle ear mucos a for adherent bacteria over a 14 day time period. Via fluorescent- an d transmission electron-microscopy, we found that NTHi preferentially adhered not to the epithelial cells but to the mucus in the ET and gra dually ascended this tubal organ, reaching the middle ear approximatel y 10 days after intranasal inoculation of adenovirus-infected animals. The number of NTHi adherent to mucus at the pharyngeal portion of the ET increased significantly in the first 4 days after inoculation of t he nares whereas the number of adherent bacteria in both the mid and t ympanic portions of the ET increased more gradually over time. NTHi we re not observed in the middle ear until approximately 7-10 days after inoculation of the nares which was coincident with the onset of clinic al signs of OM. These data confirmed our earlier in vitro investigatio n which suggested that adherence to and growth within stagnant mucus w ithin a ET compromised by adenovirus was a possible mechanism by which NTHi, resident in the nasopharynx, might gain access to the middle ea r and induce OM. (C) 1997 Academic Press Limited.