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Plasmid-determined resistance to fosfomycin in Serratia marcescens
Abstract:
Multiple-antibiotic-resistant strains of Serratia marcescens isolated from hospitalized patients were examined for their ability to transfer antibiotic resistance to Escherichia coli by conjugation. Two different patterns of linked transferable resistance were found among the transconjugants. The first comprised resistance to carbenicillin, streptomycin, and fosfomycin; the second, and more common, pattern included resistance to carbenicillin, streptomycin, kanamycin, gentamicin, tetracycline, chloramphenicol, sulfonamide, and fosfomycin. The two types of transconjugant strains carried a single plasmid of either 57 or 97 megadaltons in size. Both of these plasmids are present in parental S. marcescens strains resistant to fosfomycin. The 57-megadalton plasmid was transformed into E. coli.
Insights
Multiple-antibiotic-resistant Serratia marcescens strains transferred resistance genes to Escherichia coli. These transfers involved plasmids carrying linked resistance patterns, highlighting potential for multidrug resistance spread in hospitals.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Hospital-acquired infections pose significant challenges due to multidrug-resistant (MDR) pathogens.
- Serratia marcescens is an opportunistic pathogen frequently implicated in hospital-acquired infections.
- Understanding the mechanisms of antibiotic resistance transfer is crucial for infection control.
Purpose of the Study:
- To investigate the conjugative transfer of antibiotic resistance from clinical isolates of Serratia marcescens to Escherichia coli.
- To characterize the plasmids mediating antibiotic resistance transfer.
- To identify the patterns of linked antibiotic resistance genes transferred.
Main Methods:
- Conjugation experiments were performed to transfer antibiotic resistance from Serratia marcescens to Escherichia coli.
- Transconjugant strains were analyzed for antibiotic resistance profiles.
- Plasmid DNA was isolated and characterized by size (megadaltons).
- Plasmid transformation into E. coli was performed.
Main Results:
- Two distinct patterns of transferable antibiotic resistance were identified in Serratia marcescens.
- The first pattern included resistance to carbenicillin, streptomycin, and fosfomycin.
- The second, more common pattern, conferred resistance to a broader spectrum of antibiotics: carbenicillin, streptomycin, kanamycin, gentamicin, tetracycline, chloramphenicol, sulfonamide, and fosfomycin.
- These resistance patterns were mediated by single plasmids of 57 or 97 megadaltons.
- Both plasmids were present in fosfomycin-resistant parental S. marcescens strains.
- The 57-megadalton plasmid was successfully transformed into E. coli.
Conclusions:
- Serratia marcescens clinical isolates possess plasmids capable of transferring multiple antibiotic resistances to Escherichia coli via conjugation.
- The identified plasmids carry linked resistance genes, contributing to the spread of multidrug resistance.
- The findings underscore the importance of monitoring antibiotic resistance mechanisms in hospital settings to prevent the dissemination of MDR strains.