Characterization of ampicillin resistance plasmids of Haemophilus ducreyi and Neisseria gonorrhoeae with regard to location of origin of transfer and mobilization by a conjugative plasmid of Haemophilus ducreyi.

Restriction endonuclease maps of the ampicillin resistance plasmids of Haemophilus ducreyi and Neisseria gonorrhoeae show marked structural similarities. Transfer frequencies obtained by mobilization correlated with physical structure and were enhanced by increased homology with the conjugative plasmid. The origin of transfer of each plasmid was located within a specific restriction fragment.