Prevalence of the hifBC, hmw1A, hmw2A, hmwC, and hia Genes in Haemophilus influenzae Isolates.
Adherence of Haemophilus influenzae to respiratory epithelial cells is the first step in the pathogenesis of H. influenzae infection and is facilitated by the action of several adhesins located on the surface of the bacteria. In this study, prevalences of hifBC, which represent the pilus gene cluster; hmw1A, hmw2A, and hmwC, which represent high-molecular-weight (HMW) adhesin genes; and hia, which represents H. influenzae adhesin (Hia) genes were determined among clinical isolates of encapsulated type b (Hib) and nonencapsulated (NTHi) H. influenzae. hifBC genes were detected in 109 of 170 (64%) Hib strains and in 46 of 162 (28%) NTHi isolates (P = 0.0001) and were more prevalent among the invasive type b strains than invasive NTHi strains (P = 0.00003). Furthermore, hifBC genes were significantly more prevalent (P = 0.0398) among NTHi throat isolates than NTHi middle ear isolates. hmw1A, hmw2A, hmwC, and hia genes were not detected in Hib strains. Among NTHi isolates, the prevalence of hmw1A was 51%, the prevalence of hmw2A was 23%, the prevalence of hmwC was 48%, and the prevalence of hia was 33%. The hmw genes were significantly more prevalent among middle ear than throat isolates, while hia did not segregate with a respiratory tract site. These results show the variability of the presence of adhesin genes among clinical H. influenzae isolates and suggest that hemagglutinating pili may play a larger role in H. influenzae nasopharyngeal colonization than in acute otitis media whereas the HMW adhesins may be virulence factors for acute otitis media.
Ecevit
I Zafer
IZ
Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109-0244, USA.
McCrea
Kirk W
KW
Pettigrew
Melinda M
MM
Sen
Ananda
A
Marrs
Carl F
CF
Gilsdorf
Janet R
JR
D018829:Adhesins, Bacterial / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D005798:Genes, Bacterial; D006193:Haemophilus influenzae / Q000235:genetics*; D006801:Humans; D018832:Molecular Chaperones / Q000235:genetics*; D005810:Multigene Family; D009305:Nasopharynx / Q000382:microbiology
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C117431:HMW1 protein, bacteria; C117432:HMW2 protein, bacteria; C429644:Hia adhesin; C090993:HifB protein, Haemophilus influenzae; C090994:HifC protein, Haemophilus influenzae; D018832:Molecular Chaperones