An isogenic hemoglobin receptor-deficient mutant of Haemophilus ducreyi is attenuated in the human model of experimental infection

Jaffar A. Al-Tawfiq, Kate R. Fortney, Barry P. Katz, Antoinette F. Hood, Christopher Elkins, Stanley M. Spinola

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Haemophilus ducreyi expresses a conserved hemoglobin-binding outer- membrane protein (HgbA). To test the role of HgbA in pathogenesis, we infected 9 adults with isolate 35000 and its isogenic hgbA-inactivated mutant (FX504) on their upper arms in a double-blinded, escalating dose-response study. Papules developed at similar rates at sites inoculated with the mutant or parent. The pustule-formation rate was 55% (95% confidence interval [CI], 30.8%-78.5%) at parent sites and 0 (95% CI, 0-10.5%) at mutant sites (P < .0001). The recovery rate of H. ducreyi from surface cultures was 16% (n = 142) from parent sites and 0 (n = 213) from mutant sites (P < .0001). H. ducreyi was recovered at biopsy from 6 of 7 parent sites and from 0 of 3 mutant sites. The results indicate that hemoglobin may be a critical source of heme or iron for the establishment of H. ducreyi infection in humans.

Original languageEnglish (US)
Pages (from-to)1049-1054
Number of pages6
JournalJournal of Infectious Diseases
Issue number3
StatePublished - Apr 19 2000


ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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