Plasmid-borne streptothricin resistance in gram-negative bacteria
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Abstract:
Plasmids, which code for a new type of drug resistance due to the acetylation of streptothricin and belonging to various incompatibility groups (I1, I2, W3, FII, S, X, and N) were identified in gram-negative bacteria. The gene for the acetyltransferase is closely linked to a gene for the streptomycin/spectinomycin adenylyltransferase AAD-3" on a novel type of a transposon, designated Tn1825. This is related to Tn7.
Insights
New drug resistance plasmids were found in gram-negative bacteria, conferring resistance to streptothricin via acetylation. A novel transposon, Tn1825, carries the resistance gene linked to streptomycin/spectinomycin adenylyltransferase genes.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Plasmids are key vectors for antibiotic resistance gene dissemination.
- Streptothricin resistance is often mediated by enzymatic inactivation.
- Gram-negative bacteria harbor diverse plasmid types.
Purpose of the Study:
- To identify and characterize plasmids conferring novel drug resistance in gram-negative bacteria.
- To investigate the genetic basis of streptothricin resistance.
- To determine the genetic elements involved in the spread of this resistance.
Main Methods:
- Plasmid DNA isolation and characterization.
- Bacterial conjugation and transformation experiments.
- Gene sequencing and analysis of transposon structures.
Main Results:
- Plasmids conferring streptothricin resistance through acetylation were identified in gram-negative bacteria.
- These plasmids belonged to multiple incompatibility groups (I1, I2, W3, FII, S, X, N).
- A novel transposon, Tn1825, related to Tn7, was found to carry the acetyltransferase gene linked to AAD-3 (streptomycin/spectinomycin adenylyltransferase).
Conclusions:
- A new mechanism of streptothricin resistance mediated by plasmid-borne acetyltransferase has been identified.
- The novel transposon Tn1825 plays a role in the genetic organization and potential spread of this resistance.
- These findings highlight the dynamic nature of antibiotic resistance in gram-negative pathogens.