title: Adhesin genes and serum resistance in Haemophilus influenzae type f isolates.
abstract: The incidence of invasive infections due to Haemophilus influenzae has decreased significantly in developed countries with high rates of vaccination against H. influenzae serotype b (Hib). This vaccine provides no protection against H. influenzae serotype f (Hif), typically associated with invasive infections in adults with chronic disease and/or immunodeficiency, and rarely in otherwise healthy adults and children. The specific properties of Hif associated with virulence remain largely uncharacterized. A panel of 26 Hif strains consisting of both invasive disease-associated and mucosal surface non-invasive disease-associated isolates was surveyed by DNA fingerprinting, biotyping and PCR detection of hmw1, hmw2, hsf, the hif fimbrial locus and the lipo-oligosaccharide (LOS) biosynthetic island, and assessment of β-lactamase expression and determination of resistance to the bactericidal activity of normal adult human serum. Repetitive sequence-based PCR fingerprinting differentiated the 26 strains into three clusters, with the majority of isolates (22/26, 84.6 %) clustered into a single indistinguishable group. Most isolates (24/26, 92.3 %) were of biotype I and two isolates produced β-lactamase with detection of a conjugative plasmid, and the isolates displayed a range of resistances to the bactericidal activity of human serum. All 26 isolates carried the adhesin hsf, 21 carried a partial hif fimbrial operon and 4 had the adhesin genes hmw1/2. A LOS biosynthetic island was detected in 20 isolates consisting of the genes lic2BC. It was concluded that Hif has many recognized virulence properties and comprises a relatively homogeneous group independent of the anatomical source from which it was isolated.
authors.affiliation: Divison of Pediatric Infectious Diseases, Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Watson
authors.affiliation: Center for Childhood Infections, Seattle Children's Hospital Research Institute, Seattle, Washington, USA.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Nelson
authors.affiliation: Center for Childhood Infections, Seattle Children's Hospital Research Institute, Seattle, Washington, USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Nguyen
authors.affiliation: Division of Laboratory and Genomic Medicine, Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, USA.
authors.forename: Carey-Ann D
authors.initials: CD
authors.lastname: Burnham
authors.affiliation: Department of Laboratory Medicine, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Jill E
authors.initials: JE
authors.lastname: Clarridge
authors.affiliation: Department of Laboratory Medicine, University of Washington School of Medicine, Seattle, Washington, USA.
authors.forename: Xuan
authors.initials: X
authors.lastname: Qin
authors.affiliation: Center for Childhood Infections, Seattle Children's Hospital Research Institute, Seattle, Washington, USA.
authors.forename: Arnold L
authors.initials: AL
authors.lastname: Smith
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D015373:Bacterial Typing Techniques; D053898:Biosynthetic Pathways / Q000235:genetics; D001770:Blood Bactericidal Activity; D002648:Child; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D044404:Genomic Islands; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D050296:Microbial Viability; D058889:Molecular Typing; D016133:Polymerase Chain Reaction; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018829:Adhesins, Bacterial; D004269:DNA, Bacterial; D008070:Lipopolysaccharides; D037521:Virulence Factors; C023023:lipid-linked oligosaccharides