title: Plasmid-mediated sulfonamide resistance in Haemophilus ducreyi.
abstract: Clinical isolates of Haemophilus ducreyi from patients with chancroid were shown to have one or more 4.9- to 7.0-megadalton non-self-transferable plasmids and to have in vitro resistance to sulfonamides. Transformation of Escherichia coli to sulfonamide resistance was associated with the acquisition of a 4.9-megadalton plasmid, which did not confer linked resistance to streptomycin. The guanine-plus-cytosine content of this plasmid was found to be 57%. Filter-blot hybridization and restriction endonuclease digestion studies suggested a relationship of this plasmid to RSF1010. Electron microscope heteroduplex analysis confirmed this relationship. The identification in H. ducreyi of a plasmid closely related to plasmids found in enteric species, rather than transposition of a resistance determinant to an indigenous plasmid, suggests that further dissemination of the enteric plasmid pool to this genus is possible since plasmid transfer between certain Haemophilus species is readily demonstrated.
mesh_terms: D004720:Endonucleases / Q000032:analysis; D004926:Escherichia coli / Q000235:genetics; D006191:Haemophilus ducreyi / Q000187:drug effects / Q000235:genetics*; D006824:Hybridization, Genetic; D011815:R Factors; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: D013449:Sulfonamides; D004720:Endonucleases