Related Experiment Videos
An investigation of plasmids from Staphylococcus aureus that mediate resistance to mupirocin and tetracycline
C Needham1, M Rahman, K G Dyke
1Department of Microbial Diseases, St John's Institute of Dermatology, St Thomas' Hospital, London, UK.
Abstract:
Plasmids conferring mupirocin resistance were prepared from isolates of Staphylococcus aureus obtained from four patients in the same ward. The plasmids are related and in all of them the gene conferring mupirocin resistance (mupA) is flanked by copies of IS257 in direct repeat. In two plasmids mupA and IS257 have been duplicated and in one of these plasmids (pJ3358) a small pT181-like plasmid conferring tetracycline resistance is present flanked by copies of IS257. Filter mating with a strain containing pJ3358 as donor and selection on tetracycline sometimes resulted in transfer of the pT181-like plasmid containing a copy of IS257. Analysis showed that the pT181-like plasmid with the insertion of IS257 is present in high copy number and that the IS257 element is inserted in the copy number control region of the plasmid.
Insights
Plasmids carrying the mupirocin resistance gene (mupA) in Staphylococcus aureus were studied. These plasmids show IS257 elements flanking the mupA gene, indicating potential mobile genetic element involvement in resistance.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Mupirocin resistance in Staphylococcus aureus is a growing clinical concern.
- Understanding the genetic mechanisms of resistance is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate the genetic structure of plasmids conferring mupirocin resistance in Staphylococcus aureus.
- To identify the role of mobile genetic elements, specifically IS257, in the dissemination of mupirocin resistance.
Main Methods:
- Plasmid DNA isolation from Staphylococcus aureus clinical isolates.
- Molecular analysis including gene sequencing and identification of insertion sequences (IS257).
- Bacterial conjugation experiments to assess plasmid transfer.
Main Results:
- Plasmids conferring mupirocin resistance (mupA gene) were identified in Staphylococcus aureus.
- The mupA gene was consistently flanked by IS257 insertion sequences in direct repeat.
- Duplication of mupA and IS257 was observed in some plasmids.
- A tetracycline resistance plasmid (pT181-like) was found integrated into a mupirocin resistance plasmid, also flanked by IS257.
- Successful transfer of the tetracycline resistance plasmid with IS257 was demonstrated via filter mating.
- The integrated IS257 element was found to be in the copy number control region of the tetracycline resistance plasmid, leading to high copy numbers.
Conclusions:
- IS257 insertion sequences play a significant role in the structure and potential mobilization of mupirocin resistance genes in Staphylococcus aureus.
- The findings suggest a mechanism for the co-dissemination of antibiotic resistance genes through the action of mobile genetic elements.