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Plasmid mediated silver resistance in Acinetobacter baumannii
1Department of Microbiology, University of Poona, Pune, India.
Abstract:
Acinetobacter baumannii BL88, an environmental isolate, was resistant to 13 metals and 10 antibiotics. Plumbagin cured resistance to silver, cadmium, antimony, streptomycin and ampicillin at varying frequencies. However, only silver resistance transferred (1 x 10(-6) recepient-1) to Escherichia coli K12 during conjugation. Correspondingly there was transfer of a 54 kb plasmid (pUPI199) from A. baumannii BL88. The plasmid transformed E. coli DH5 alpha cells at a frequency of 1 x 10(-8) recepient-1. The growth rate of E. coli DH5 alpha (pUPI199) was slower as compared with E. coli DH5 alpha. Plasmid pUPI199 was 76 and 9.6% stable in the host A. baumannii BL88 in the presence and absence of selection pressure, respectively. A. baumannii BL88 was found to accumulate and retain silver whereas E. coli DH5 alpha (pUPI199) effluxed 63% of the accumulated silver ions.
Insights
Acinetobacter baumannii BL88, resistant to multiple metals and antibiotics, transferred silver resistance via plasmid pUPI199 to Escherichia coli. This plasmid impacted E. coli
Area of Science:
- Microbiology
- Molecular Biology
- Environmental Science
Background:
- Acinetobacter baumannii BL88, an environmental isolate, exhibits resistance to 13 metals and 10 antibiotics.
- Plumbagin, a natural compound, was investigated for its ability to eliminate plasmid-mediated resistance in bacteria.
Purpose of the Study:
- To investigate the curing of metal and antibiotic resistance in Acinetobacter baumannii BL88 using plumbagin.
- To characterize the transfer of resistance and the associated plasmid in Escherichia coli.
Main Methods:
- Treatment of Acinetobacter baumannii BL88 with plumbagin to cure resistance.
- Conjugation experiments to transfer resistance to Escherichia coli K12.
- Plasmid isolation, transformation into E. coli DH5 alpha, and stability studies.
- Analysis of silver ion accumulation and efflux in host bacteria.
Main Results:
- Plumbagin cured resistance to silver, cadmium, antimony, streptomycin, and ampicillin in A. baumannii BL88.
- Silver resistance was transferred to E. coli K12 via conjugation, associated with a 54 kb plasmid (pUPI199).
- The plasmid transformed E. coli DH5 alpha cells and resulted in slower growth rates.
- Plasmid pUPI199 showed differential stability in A. baumannii BL88 under selection pressure.
- A. baumannii BL88 accumulated silver, while E. coli DH5 alpha (pUPI199) effluxed a significant portion of accumulated silver ions.
Conclusions:
- Plasmid pUPI199 mediates silver resistance in Acinetobacter baumannii and can be transferred to Escherichia coli.
- The presence of pUPI199 affects the growth rate and silver ion handling in E. coli.
- Understanding plasmid-mediated resistance mechanisms is crucial for managing bacterial infections and environmental contamination.