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Emergence of high-level mupirocin resistance in methicillin-resistant Staphylococcus aureus in Western Australia
E E Udo1, J W Pearman, W B Grubb
1School of Biomedical Sciences, Curtin University of Technology, Perth, Western Australia.
Abstract:
Six mupirocin-resistant Staphylococcus aureus were isolated from patients living in the northern part of Western Australia (WA). They were all resistant to methicillin, tetracycline, trimethoprim and cadmium and harboured similar 41.4 kb plasmids. Transfer and curing experiments with one of the isolates, WBG7569, demonstrated that the 41.4 kb plasmid encoded resistance to mupirocin, tetracycline, trimethoprim and cadmium. The isolates were compared by pulsed-field gel electrophoresis with methicillin-resistant S. aureus (MRSA) previously isolated from the Kimberley region in the northern-most part of WA (WA MRSA). The mupirocin-resistant isolates were found to be closely related to WA MRSA suggesting that they were WA MRSA which had acquired a new multiple-resistance plasmid encoding high-level mupirocin resistance.
Insights
Six mupirocin-resistant Staphylococcus aureus strains were identified in Western Australia. These strains were closely related to existing methicillin-resistant S. aureus (MRSA) and had acquired a new plasmid conferring multiple drug resistance.
Area of Science:
- Microbiology
- Infectious Diseases
- Genetics
Background:
- Mupirocin is a key antibiotic for treating Staphylococcus aureus infections.
- Antibiotic resistance in Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA), is a growing global health concern.
- The emergence of mupirocin resistance in MRSA strains poses a significant challenge for clinical management.
Purpose of the Study:
- To investigate the characteristics of mupirocin-resistant Staphylococcus aureus isolates from Northern Western Australia.
- To determine the genetic relatedness of these isolates to previously identified Western Australian MRSA (WA MRSA).
- To identify the genetic elements responsible for the observed multidrug resistance.
Main Methods:
- Isolation and characterization of mupirocin-resistant Staphylococcus aureus.
- Plasmid analysis, including transfer and curing experiments.
- Pulsed-field gel electrophoresis (PFGE) for strain typing.
- Comparison with existing WA MRSA isolates.
Main Results:
- Six mupirocin-resistant Staphylococcus aureus isolates were identified in Northern Western Australia.
- All isolates exhibited resistance to methicillin, tetracycline, trimethoprim, and cadmium, and carried similar 41.4 kb plasmids.
- Transfer and curing experiments confirmed that the 41.4 kb plasmid encoded resistance to all tested antibiotics and cadmium.
- PFGE analysis revealed that these isolates were closely related to WA MRSA.
Conclusions:
- The mupirocin-resistant Staphylococcus aureus isolates are likely WA MRSA strains that have acquired a novel multidrug-resistance plasmid.
- This acquisition confers high-level mupirocin resistance, alongside resistance to other antibiotics and cadmium.
- The findings highlight the ongoing evolution of antibiotic resistance in Staphylococcus aureus within Australia.