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A new streptomycin-resistance plasmid from Staphylococcus hyicus and its structural relationship to other
1Institut für Bakteriologie und Immunologie, Justus Liebig-Universität, Giessen, FRG.
Abstract:
A small plasmid of 4.4 kb encoding resistance to streptomycin (Smr) was detected in a multiresistant Staphylococcus hyicus culture from a piglet with exudative epidermitis. The plasmid-encoded properties were determined by interspecies protoplast transformation experiments. This plasmid was further characterised by restriction endonuclease analysis and a preliminary restriction map was constructed. The plasmid from S. hyicus that conferred streptomycin resistance was designated as pSAI-1. It showed some structural homology with the streptomycin-chloramphenicol resistance plasmid pSK68 from S. aureus of human origin. The MIC of streptomycin in resistance mediated by pSAI-1 was about 10 times higher than the MICs in resistance mediated by Smr plasmids from human S. aureus strains.
Insights
A novel plasmid, pSAI-1, conferring streptomycin resistance was identified in Staphylococcus hyicus from a piglet. This plasmid exhibits higher resistance levels compared to similar plasmids found in human Staphylococcus aureus strains.
Area of Science:
- Veterinary Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Multidrug resistance in bacteria is a growing concern in both human and animal health.
- Staphylococcus hyicus is a significant pathogen in swine, causing diseases like exudative epidermitis.
- Plasmids are key mobile genetic elements that facilitate the spread of antimicrobial resistance.
Purpose of the Study:
- To identify and characterize the plasmid responsible for streptomycin resistance in a multiresistant Staphylococcus hyicus isolate.
- To compare the streptomycin resistance conferred by this plasmid with known resistance plasmids from Staphylococcus aureus.
Main Methods:
- Detection and isolation of a plasmid from Staphylococcus hyicus.
- Interspecies protoplast transformation experiments to determine plasmid-encoded properties.
- Restriction endonuclease analysis to characterize the plasmid's genetic structure.
- Construction of a preliminary restriction map for the identified plasmid.
Main Results:
- A 4.4 kb plasmid, designated pSAI-1, encoding streptomycin resistance (Smr) was identified in Staphylococcus hyicus.
- Plasmid pSAI-1 conferred streptomycin resistance upon transformation into other bacterial species.
- Restriction analysis revealed structural homology between pSAI-1 and a streptomycin-chloramphenicol resistance plasmid (pSK68) from Staphylococcus aureus.
- The minimum inhibitory concentration (MIC) of streptomycin mediated by pSAI-1 was approximately 10-fold higher than that mediated by Smr plasmids from human S. aureus strains.
Conclusions:
- The plasmid pSAI-1 is a novel streptomycin resistance determinant in Staphylococcus hyicus of animal origin.
- pSAI-1 represents a distinct streptomycin resistance mechanism with potentially higher efficacy than those found in human S. aureus.
- Understanding such animal-derived resistance plasmids is crucial for monitoring and controlling antimicrobial resistance spread.