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Transfer of resistance determinants from a multi-resistant Staphylococcus aureus isolate
1School of Medical Technology, Curtin University of Technology, Perth, Western Australia.
Abstract:
The clinical isolate Staphylococcus aureus WBG1024 was resistant to cadmium, benzyl penicillin, kanamycin, neomycin, streptomycin, tetracycline and trimethoprim and harboured a conjugative plasmid pWBG637 (34.5 kb) and non-conjugative plasmids of 23.8, 4.4, 2.8 and 1.9 kb. Transduction and mixed-culture transfer experiments demonstrated that the 4.4-kb plasmid (pWBG632) encoded resistance to tetracycline and the 23.8-kb plasmid (pWBG628) encoded resistance to cadmium, benzyl penicillin, kanamycin, neomycin and streptomycin. The conjugative plasmid pWBG637 was able to mobilise a further 4.4-kb plasmid (pWBG633) encoding streptomycin resistance and recombined with the multiresistance plasmid pWBG628 to produce transconjugantes of various resistance phenotypes.
Insights
This study identifies specific plasmids in Staphylococcus aureus WBG1024 responsible for antibiotic resistance. Researchers mapped tetracycline resistance to a 4.4-kb plasmid and multiple resistances to a 23.8-kb plasmid.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Clinical isolates of Staphylococcus aureus often exhibit multidrug resistance.
- Understanding the genetic basis of this resistance is crucial for effective treatment strategies.
Purpose of the Study:
- To characterize the plasmids harbored by Staphylococcus aureus WBG1024.
- To determine the genetic determinants of antibiotic resistance in this clinical isolate.
Main Methods:
- Plasmid isolation and characterization.
- Conjugation and transduction experiments for gene mapping.
- Phenotypic analysis of antibiotic resistance.
Main Results:
- Staphylococcus aureus WBG1024 carried a conjugative plasmid (pWBG637) and several non-conjugative plasmids.
- A 4.4-kb plasmid (pWBG632) conferred tetracycline resistance.
- A 23.8-kb plasmid (pWBG628) encoded resistance to cadmium, benzyl penicillin, kanamycin, neomycin, and streptomycin.
- The conjugative plasmid facilitated the transfer of a streptomycin resistance plasmid (pWBG633) and recombined with pWBG628.
Conclusions:
- Specific plasmids harbor distinct antibiotic resistance genes in Staphylococcus aureus.
- Plasmid-mediated resistance mechanisms contribute to the multidrug-resistant phenotype.
- Conjugative plasmids play a role in the dissemination of resistance genes.