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Transfer of plasmid-borne resistance from a multiply-resistant Staphylococcus aureus isolate, WBG1022
1School of Biomedical Sciences, Curtin University of Technology, Perth, Australia.
Abstract:
Staphylococcus aureus isolate, WBG1022, was resistant to penicillin, kanamycin, neomycin, streptomycin, chloramphenicol, trimethoprim, cadmium, and ethidium bromide and harbored plasmids of 34.5, 24.5, 4.4, 3.2, and 2.6 kilobases. The plasmids were transferred in mixed-culture transfer and conjugation experiments. No resistance phenotype was associated with the 2.6-kb plasmid. The 3.2-kb and 4.4-kb plasmids encoded chloramphenicol and streptomycin resistance respectively. The 24.5-kb plasmid, pWBG626, encoded joint resistance to penicillin, kanamycin, neomycin, and ethidium bromide. Resistance to trimethoprim and cadmium were chromosomal. The 34.5-kb plasmid, pWBG661, had no resistance phenotype but was found to be conjugative. It also mobilized the 4.4-kb and 24.5-kb plasmids in WBG1022. Restriction endonuclease analysis of pWBG661 with EcoRI, ClaI, PvuII, and BglII restriction enzymes demonstrated that pWBG661 was identical to two previously isolated S. aureus conjugative plasmids, pWBG620 and pWBG637, that also lack resistance phenotypes.
Insights
This study characterized antibiotic resistance plasmids in Staphylococcus aureus WBG1022. A 34.5-kb conjugative plasmid, pWBG661, mobilized other resistance plasmids, highlighting potential mechanisms of antibiotic resistance spread.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Staphylococcus aureus is a significant human pathogen.
- Antibiotic resistance in S. aureus poses a major public health threat.
- Plasmids play a crucial role in the dissemination of antibiotic resistance genes.
Purpose of the Study:
- To identify and characterize the plasmids harbored by the multidrug-resistant Staphylococcus aureus isolate WBG1022.
- To determine the genetic basis of antibiotic and heavy metal resistance in WBG1022.
- To investigate the transferability and mobilization capabilities of the identified plasmids.
Main Methods:
- Plasmid isolation and characterization.
- Conjugation experiments for plasmid transfer.
- Restriction endonuclease analysis for plasmid identification.
- Determination of resistance phenotypes and their genetic linkage.
Main Results:
- WBG1022 harbored five plasmids (34.5, 24.5, 4.4, 3.2, and 2.6 kb).
- Specific plasmids were associated with resistance to penicillin, kanamycin, neomycin, streptomycin, chloramphenicol, and ethidium bromide.
- Chromosomal genes conferred resistance to trimethoprim and cadmium.
- The 34.5-kb conjugative plasmid (pWBG661) mobilized other resistance plasmids and was identical to previously identified S. aureus conjugative plasmids.
Conclusions:
- The study elucidated the plasmid-mediated resistance mechanisms in S. aureus WBG1022.
- Conjugative plasmids, like pWBG661, can facilitate the spread of antibiotic resistance.
- Understanding plasmid biology is critical for combating antibiotic resistance in S. aureus.