Infection and Immunity, January 1999, p. 449-454, Vol. 67, No. 1
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Edward Mallinckrodt Department of Pediatrics
and Department of Molecular Microbiology,
Received 24 June 1998/Returned for modification 19 August
1998/Accepted 15 October 1998
The HMW1 and HMW2 proteins, Hia, and hemagglutinating pili are
important adherence factors in nontypeable Haemophilus
influenzae. To gain insight into the relative importance of these
adhesins in nasopharyngeal colonization and localized respiratory tract disease, we assessed their expression in matched nasopharyngeal and
middle ear isolates of nontypeable H. influenzae from 17 children with acute otitis media. In all patients, including 11 with
bilateral disease, the matched isolates were isogenic based on total
protein profiles and genomic fingerprints. Of the nasopharyngeal
isolates, 14 expressed only HMW1/HMW2-like proteins, 1 expressed only
Hia, 1 expressed only pili, and 1 expressed both Hia and pili. Further analysis revealed concordance between nasopharyngeal isolates and the
matched middle ear isolates for expression of the HMW1/HMW2-like proteins and Hia. In contrast, in the two children whose nasopharynges were colonized by piliated organisms, the corresponding middle ear
isolates were nonpiliated and could not be enriched for piliation. Nevertheless, Southern analysis revealed that these two middle ear
isolates contained all five hif genes required for pilus
biogenesis and had no evidence of major genetic rearrangement. In
summary, the vast majority of isolates of nontypeable H. influenzae associated with acute otitis media express
HMW1/HMW2-like proteins, with expression present in both the
nasopharynx and the middle ear. A smaller fraction of nasopharyngeal
isolates express pili, while isogenic strains recovered from the middle
ear are often refractory to enrichment for piliation. We speculate that
the HMW adhesins and Hia are important at multiple steps in the
pathogenesis of otitis media while pili contribute to early
colonization and then become dispensable.
*
Corresponding author. Mailing address: Edward
Mallinckrodt Department of Pediatrics and Department of Molecular
Microbiology, Washington University School of Medicine, 660 South
Euclid Ave., Box 8230, St. Louis, MO 63110. Phone: (314) 362-5401. Fax:
(314) 362-1232. E-mail: krasan_g{at}kids.wustl.edu.
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