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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.

Adhesin Expression in Matched Nasopharyngeal and Middle Ear Isolates of Nontypeable Haemophilus influenzae from Children with Acute Otitis Media

Graham P. Krasan,1,2,* David Cutter,1,2 Stan L. Block,3 and Joseph W. St. Geme III1,2

Edward Mallinckrodt Department of Pediatrics and Department of Molecular Microbiology, Washington University School of Medicine,1 and Division of Infectious Diseases, St. Louis Children's Hospital,2 St. Louis, Missouri, and Pediatric Research Inc., Bardstown, Kentucky3

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.

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.


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