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Transmissible mupirocin resistance in Staphylococcus aureus
M Rahman1, W C Noble, B Cookson
1Department of Microbiology, Institute of Dermatology, United Medical School, London.
Abstract:
The spread of two strains of Staphylococcus aureus with high level resistance to mupirocin is described. The resistance proved to be easily transferred to other S. aureus strains by filter mating experiments and on the skin of mice. No plasmid band corresponding to the resistance could be demonstrated by agarose gel electrophoresis or by caesium chloride gradient centrifugation but cleavage of 'chromosomal' DNA from resistant recipients showed bright bands of DNA absent from sensitive controls.
Insights
High-level mupirocin resistance in Staphylococcus aureus strains spread easily between bacteria and on mouse skin. This resistance was linked to chromosomal DNA, not plasmids, indicating a novel genetic mechanism for antibiotic resistance.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Antibiotic resistance is a growing global health concern.
- Staphylococcus aureus is a common pathogen, and resistance to antibiotics like mupirocin complicates treatment.
- Understanding the mechanisms of resistance spread is crucial for infection control.
Purpose of the Study:
- To describe the spread of high-level mupirocin resistance in Staphylococcus aureus.
- To investigate the genetic basis of this resistance.
- To determine the transferability of the resistance.
Main Methods:
- Filter mating experiments were used to assess resistance transfer between S. aureus strains.
- In vivo studies on mouse skin were conducted to evaluate resistance spread.
- Agarose gel electrophoresis and caesium chloride gradient centrifugation were employed to detect plasmids.
- Chromosomal DNA from resistant and sensitive strains was analyzed using DNA cleavage techniques.
Main Results:
- Two strains of Staphylococcus aureus exhibiting high-level mupirocin resistance were identified.
- The resistance was readily transferable to other S. aureus strains via filter mating.
- Resistance transfer was also demonstrated on the skin of mice.
- No plasmid DNA correlated with the resistance was detected using standard methods.
- Analysis of chromosomal DNA revealed unique DNA bands in resistant strains compared to sensitive ones.
Conclusions:
- High-level mupirocin resistance in these S. aureus strains is transferable.
- The genetic determinant for resistance appears to be integrated into the bacterial chromosome.
- This finding suggests a chromosomal mechanism for the spread of mupirocin resistance in S. aureus.