title: Absence of extracellular enzyme activity and cytotoxicity in cell-free culture filtrates of Haemophilus ducreyi.
abstract: Ten isolates of Haemophilus ducreyi, including seven clinical isolates and three laboratory reference strains, were assessed for their ability to produce extracellular enzymes which might contribute to their pathogenicity. Protease, elastase, lecithinase, lipase or collagenase enzyme activity were not detected in culture filtrates from any of the isolates tested using either plate or spectrophotometrical assays. Furthermore, cell-free culture filtrates did not exhibit cytotoxic activity in vitro when tested using either an established tissue culture cell line (Vero) or a primary cell culture of human keratinocytes. These results suggest that extracellular products do not play a role in host invasion or production of tissue damage by H. ducreyi.
authors.affiliation: Department of Dermatology, Ludwig-Maximilians-University, Munich, F.R.G.
authors.forename: D
authors.initials: D
authors.lastname: Abeck
authors.forename: A P
authors.initials: AP
authors.lastname: Johnson
authors.forename: A
authors.initials: A
authors.lastname: Hartinger
authors.forename: M
authors.initials: M
authors.lastname: Kollmann
authors.forename: H C
authors.initials: HC
authors.lastname: Korting
authors.forename: R C
authors.initials: RC
authors.lastname: Ballard
authors.forename: O
authors.initials: O
authors.lastname: Braun-Falco
mesh_terms: D002474:Cell-Free System; D002602:Chancroid / Q000382:microbiology / Q000473:pathology*; D010450:Endopeptidases / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D006191:Haemophilus ducreyi / Q000201:enzymology* / Q000472:pathogenicity; D006801:Humans; D003012:Microbial Collagenase / Q000378:metabolism; D010196:Pancreatic Elastase / Q000378:metabolism; D010740:Phospholipases / Q000378:metabolism
chemical_list: D004798:Enzymes; D010740:Phospholipases; D010450:Endopeptidases; D010196:Pancreatic Elastase; D003012:Microbial Collagenase