INTERACTION OF FIMBRIATED AND NONFIMBRIATED STRAINS OF UNENCAPSULATEDHAEMOPHILUS-INFLUENZAE WITH HUMAN RESPIRATORY-TRACT MUCUS IN-VITRO

Adherence to mucus may influence bacterial colonization of the respira tory tract, Clinical isolates of nontypable Haemophilus influenzas (NT Hi) from the respiratory tract are often fimbriated, We wondered wheth er fimbriated strains have a different adherence from related nonfimbr iated strains. A microtitre plate assay has been developed to study ad herence of nontypable H. influenzae to mucus. Wells were coated by inc ubation either with sol phase of sterile mucoid secretions or with pur ified preparations of mucins, Two laboratory pairs of fimbriated (F+) and nonfimbriated (F-) nontypable H. influenzas, and six fresh clinica l isolates of fimbriated nontypable H. influenzas each with nonfimbria ted partners derived by serial passage on agar, were cultured to mid-l og phase, washed, and then added to the wells, They were then incubate d at 37 degrees C for 30 min before washing to remove unbound bacteria , Adherent bacteria were desorbed by agitation with 0.5% Tween 80 and a viable count performed. The two fimbriated laboratory strains (n=12 and n=17), and 5 of the 6 fimbriated clinical isolates were more adher ent to sol phase than their respective nonfimbriated partners, Two non fimbriated clinical isolates were more adherent to plastic than their fimbriated partners, A fimbriated laboratory strain was more adherent than its nonfimbriated partner both to a purified preparation of high molecular mass mucin and to the glycopeptide fraction of the same. We conclude that fimbriated strains of nontypable H. influenzae have incr eased adherence to sol phase of mucus and purified human respiratory t ract mucin, The interactions of fimbriae with mucus are likely to be c omplex, and may involve both nonspecific and specific interactions.