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Amikacin resistance mediated by multiresistance transposon Tn2424
Abstract:
Tn2424, a multiresistance transposon 25 kilobases long, was isolated from IncFII plasmid NR79. Tn2424 transposed resistance to sulfonamides, streptomycin and spectinomycin, mercuric chloride, chloramphenicol, and amikacin with a frequency of 6 X 10(-5). Resistance to amikacin was mediated by a 6'-N-acetyltransferase, which conferred higher levels of resistance in Pseudomonas aeruginosa than in Escherichia coli. A restriction analysis and cloning experiments resulted in a physical and functional map of Tn2424. Comparison by a heteroduplex technique revealed that Tn2424 includes the total sequence of Tn21 and two additional DNA fragments that are 1.8 and 4 kilobases long.
Insights
A novel multiresistance transposon, Tn2424, was identified, conferring resistance to multiple antibiotics and heavy metals. This transposon contains the Tn21 sequence plus additional DNA, impacting resistance levels in bacteria like Pseudomonas aeruginosa.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Multiresistance transposons contribute significantly to the spread of antibiotic resistance.
- IncFII plasmids are known vectors for mobile genetic elements, including transposons.
- Understanding transposon structure and function is crucial for combating antimicrobial resistance.
Purpose of the Study:
- To isolate and characterize a novel multiresistance transposon, Tn2424.
- To determine the genetic basis of resistance conferred by Tn2424.
- To elucidate the molecular structure of Tn2424 through physical and functional mapping.
Main Methods:
- Isolation of transposon Tn2424 from IncFII plasmid NR79.
- Transposition assays to determine resistance profiles and frequencies.
- Restriction analysis and molecular cloning for genetic mapping.
- Heteroduplex analysis for sequence comparison.
Main Results:
- Tn2424 confers resistance to sulfonamides, streptomycin, spectinomycin, mercuric chloride, chloramphenicol, and amikacin.
- Amikacin resistance is mediated by a 6'-N-acetyltransferase, with higher efficacy in Pseudomonas aeruginosa.
- Tn2424 is composed of the entire Tn21 sequence plus two additional DNA fragments (1.8 and 4 kb).
- A physical and functional map of Tn2424 was generated.
Conclusions:
- Tn2424 represents a significant multiresistance element with implications for bacterial adaptation.
- The novel structure of Tn2424, incorporating Tn21, highlights the dynamic nature of transposon evolution.
- Understanding Tn2424's genetic makeup and resistance mechanisms is vital for antimicrobial resistance surveillance.