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J Med Microbiol. 2013 Apr;62(Pt 4):514-24. doi: 10.1099/jmm.0.052175-0. Epub 2012 Dec 14.

Adhesin genes and serum resistance in Haemophilus influenzae type f isolates.

Author information

1
Divison of Pediatric Infectious Diseases, Department of Pediatrics, Washington University School of Medicine, St Louis, Missouri, USA. watson_m@kids.wustl.edu

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.

PMID:
23242639
PMCID:
PMC3709541
DOI:
10.1099/jmm.0.052175-0
[Indexed for MEDLINE]
Free PMC Article

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