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Transferable plasmid-mediated antibiotic resistance in Listeria monocytogenes
C Poyart-Salmeron1, C Carlier, P Trieu-Cuot
1Unité des Agents Antibactériens, Institut Pasteur, Paris, France.
Abstract:
A strain of Listeria monocytogenes, isolated from a patient with meningoencephalitis, was resistant to chloramphenicol, erythromycin, streptomycin, and tetracycline. The genes conferring resistance to these antibiotics were carried by a 37-kb plasmid, pIP811, that was self-transferable to other L monocytogenes cells, to enterococci-streptococci, and to Staphylococcus aureus. The efficacy of transfer and the stability of pIP811 were higher in enterococci-streptococci than in the other gram-positive bacteria. As indicated by nucleic acid hybridisation, the genes in pIP811 conferring resistance to chloramphenicol, erythromycin, and streptomycin were closely related to plasmid-borne determinants that are common in enterococci-streptococci. Plasmid pIP811 shared extensive sequence homology with pAM beta 1, the prototype broad host range resistance plasmid in these two groups of gram-positive cocci. These results suggest that emergence of multiple antibiotic resistance in Listeria spp is due to acquisition of a replicon originating in enterococci-streptococci. The dissemination of resistance to other strains of L monocytogenes is likely.
Insights
A Listeria monocytogenes strain acquired a plasmid conferring multiple antibiotic resistances. This plasmid, originating from enterococci-streptococci, can transfer to other bacteria, potentially spreading resistance.
Area of Science:
- Microbiology
- Genetics
- Infectious Diseases
Background:
- Listeria monocytogenes is a pathogen causing serious infections like meningoencephalitis.
- Antibiotic resistance in bacteria poses a significant public health threat.
- Understanding the mechanisms of antibiotic resistance spread is crucial for effective treatment.
Purpose of the Study:
- To investigate the genetic basis of antibiotic resistance in a clinical isolate of Listeria monocytogenes.
- To determine the transferability and stability of the resistance-conferring plasmid.
- To identify the origin of the antibiotic resistance genes.
Main Methods:
- Isolation and characterization of Listeria monocytogenes.
- Plasmid isolation and DNA hybridization techniques.
- Bacterial conjugation experiments to assess plasmid transfer.
Main Results:
- A multi-drug resistant Listeria monocytogenes strain was identified.
- A 37-kb self-transferable plasmid, pIP811, carried resistance genes for chloramphenicol, erythromycin, streptomycin, and tetracycline.
- Plasmid pIP811 showed higher transfer efficacy and stability in enterococci-streptococci.
- Resistance genes on pIP811 were homologous to enterococcal determinants and shared homology with plasmid pAM beta 1.
Conclusions:
- Multiple antibiotic resistance in Listeria spp. likely arises from acquiring replicons originating in enterococci-streptococci.
- The plasmid pIP811 facilitates the dissemination of antibiotic resistance within and potentially to other bacterial species.