Role of heme compounds and haptoglobin in Vibrio vulnificus pathogenicity

Publisher Website
Google Scholar
Abstract
An induced peritonitis model was employed in mice to determine whether heme-containing molecules enhance the lethality of infections by V. vulnificus. The lethality of i.p. inocula of the bacteria was increased by concurrent injections i.p. of Hb, methemoglobin or hematin, but not by myoglobin. Similar results were obtained in mice with phenylhydrazine-induced hemoglobinemia, in which after i.p. injections of V. vulnificus, a direct correlation between lethality and levels of plasma Hb was observed. In vitro studies indicated that the growth of V. vulnificus, which was limited in an Fe-poor medium, was enhanced by the addition of Hb in a manner similar to an inorganic Fe source, ferric ammonium citrate. These results suggest that V. vulnificus is capable of extracting Fe from Hb for use as a nutrilite, thereby promoting growth and increased lethality in the in vivo models. Further studies with human serum cultures demonstrated that the growth of V. vulnificus was not decreased when Hb added to the serum was completely complexed with haptoglobin; these results are in opposition to those with cultures of Escherichia coli. These results are discussed relative to the capacity of V. vulnificus to produce fatal human infections.