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Characterization of ampicillin resistance plasmids from Haemophilus ducreyi
Abstract:
Seven strains of Haemophilus ducreyi from diverse geographic origins were analyzed for their plasmid content. All strains were multiply resistant, but only resistance to ampicillin was transferred to Escherichia coli by transformation. The H. ducreyi plasmids encoding for ampicillin resistance were 7.4, 5.7, and 3.6 megadaltons and encoded for part or all of TnA, and ampicillin transposon. The relatedness of these plasmids was examined by restriction endonuclease digestion and DNA-DNA homology with isolated DNA fragments from TnA.
Insights
Seven Haemophilus ducreyi strains showed multiple drug resistance. Ampicillin resistance, mediated by plasmids encoding the TnA transposon, was transferable to Escherichia coli via transformation.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Haemophilus ducreyi is a Gram-negative bacterium causing chancroid.
- Understanding antimicrobial resistance mechanisms in H. ducreyi is crucial for effective treatment.
- Plasmids are known to play a significant role in bacterial resistance.
Purpose of the Study:
- To analyze the plasmid content of diverse Haemophilus ducreyi strains.
- To investigate the genetic basis of ampicillin resistance in these strains.
- To determine the transferability and characteristics of resistance-encoding plasmids.
Main Methods:
- Plasmid DNA isolation from seven H. ducreyi strains.
- Transformation experiments using Escherichia coli as a recipient.
- Plasmid characterization using restriction endonuclease digestion.
- DNA-DNA hybridization techniques to assess genetic relatedness.
Main Results:
- All analyzed H. ducreyi strains exhibited multiple drug resistance.
- Ampicillin resistance was transferable to E. coli via transformation.
- Identified plasmids mediating ampicillin resistance were 7.4, 5.7, and 3.6 megadaltons.
- These plasmids contained elements of the TnA ampicillin transposon.
Conclusions:
- Plasmids carrying the TnA transposon are responsible for ampicillin resistance in these H. ducreyi strains.
- The identified plasmids are genetically related, suggesting a common origin or evolution.
- Horizontal gene transfer of ampicillin resistance in H. ducreyi is mediated by these plasmids.