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Gentamicin-resistant staphylococci: genetics of an outbreak in a dermatology department
Abstract:
The genetics of gentamicin resistance in Staphylococcus aureus strains isolated during an outbreak of infection in dermatology department have been studied. The predominant strain of S. aureus did not appear to possess a plasmid mediating gentamicin resistance though one isolate yielded a plasmid coding for penicillin and gentamicin. Three distinct plasmids were isolated from other phage types of S. aureus which appeared towards the end of the epidemic. There appeared to be a stepwise loss of gentamicin resistance in the predominant strain.
Insights
Gentamicin resistance in Staphylococcus aureus strains during a dermatology outbreak was studied. Resistance was not plasmid-mediated in the main strain, but plasmids were found in later strains, with a stepwise loss of resistance observed.
Area of Science:
- Microbiology
- Genetics
- Epidemiology
Background:
- Staphylococcus aureus outbreaks pose significant challenges in healthcare settings.
- Understanding the genetic basis of antibiotic resistance is crucial for effective treatment.
- Gentamicin resistance in S. aureus has been a growing concern.
Purpose of the Study:
- To investigate the genetic mechanisms of gentamicin resistance in Staphylococcus aureus strains.
- To identify plasmids associated with gentamicin resistance during a specific outbreak.
- To track the evolution of resistance patterns within the predominant S. aureus strain.
Main Methods:
- Isolation and characterization of S. aureus strains from a dermatology department outbreak.
- Plasmid DNA isolation and analysis.
- Phage typing of S. aureus isolates.
- Assessment of gentamicin resistance patterns.
Main Results:
- The predominant S. aureus strain did not consistently harbor a plasmid conferring gentamicin resistance.
- One isolate contained a plasmid encoding both penicillin and gentamicin resistance.
- Three distinct plasmids were identified in later S. aureus phage types.
- A stepwise reduction in gentamicin resistance was observed in the predominant strain over time.
Conclusions:
- The genetic basis of gentamicin resistance in this S. aureus outbreak was complex and varied among strains.
- Plasmids played a role in resistance, particularly in strains emerging later in the epidemic.
- The observed stepwise loss of resistance suggests dynamic genetic changes within the bacterial population.