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R-plasmid mediated transfer of beta-lactam resistance in Bacteroides fragilis
K Yamaoka1, K Watanabe, Y Muto
1Institute of Anaerobic Bacteriology, School of Medicine, Gifu University, Japan.
Abstract:
We described plasmid mediated transfer of resistance to beta-lactam antibiotics between Bacteroides fragilis strains. Ampicillin-resistance was transferred from B. fragilis strain GAI-10150 to a B. fragilis strain JC-101 with a frequency of 10(-6)/input donor by a filter mating technique. A common plasmid band, named pBFKW1, was found in both the donor and the transconjugants. The plasmid was purified by an ethidium bromide-CsCl ultracentrifugation. The molecular size of the plasmid pBFKW1 which seemed to encode the beta-lactam resistance and beta-lactamase production was estimated ca. 40 kb by the analysis of endonuclease digest. Substrate profile of the enzymes derived from the donor and a transconjugant were of cephalosporinase character.
Insights
Bacteroides fragilis strains can transfer ampicillin resistance via plasmids. A specific plasmid, pBFKW1, was identified as responsible for mediating this beta-lactam resistance and cephalosporinase production.
Area of Science:
- Microbiology
- Molecular Biology
- Antibiotic Resistance
Background:
- Bacteroides fragilis is an opportunistic pathogen.
- Beta-lactam antibiotics are widely used for treatment.
- Antibiotic resistance in bacteria poses a significant public health threat.
Purpose of the Study:
- To investigate the mechanism of plasmid-mediated beta-lactam antibiotic resistance transfer in Bacteroides fragilis.
- To identify and characterize the plasmid responsible for ampicillin resistance.
Main Methods:
- Filter mating technique for plasmid transfer between bacterial strains.
- Ethidium bromide-CsCl ultracentrifugation for plasmid purification.
- Endonuclease digestion and analysis for plasmid size determination.
Main Results:
- Ampicillin resistance was successfully transferred between B. fragilis strains at a frequency of 10(-6)/input donor.
- A common plasmid, designated pBFKW1 (approx. 40 kb), was identified in both donor and transconjugant strains.
- Enzymes from the donor and transconjugant exhibited cephalosporinase activity, indicating beta-lactamase production.
Conclusions:
- Plasmid pBFKW1 mediates the transfer of ampicillin resistance in Bacteroides fragilis.
- The identified plasmid encodes for cephalosporinase activity, contributing to beta-lactam resistance.