title: Plasmid-coded ampicillin resistance in Haemophilus ducreyi.
abstract: Seven of the 96 ampicillin-resistant isolates of Haemophilus ducreyi reported in the preceding article (Bilgeri et al., Antimicrob. Agents Chemother. 22:686-688, 1982) were investigated and found to harbor plasmids of 3.95, 5.2, 5.8, and 6.4 megadaltons. All except the 5.8-megadalton plasmid have been shown to code for beta-lactamase. The 6.4- and 5.2-megadalton plasmids of three isolates were conjugally transferable to a streptomycin-resistant mutant of H. ducreyi at high frequencies, perhaps due to the presence in these strains of a high-molecular-weight plasmid.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D002602:Chancroid / Q000382:microbiology; D006191:Haemophilus ducreyi / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008970:Molecular Weight; D011815:R Factors; D013307:Streptomycin / Q000494:pharmacology; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000667:Ampicillin; D001618:beta-Lactamases; D013307:Streptomycin