Related Experiment Videos
Genetic basis of trimethoprim and O/129 resistance in Vibrio cholerae
Abstract:
Because of its important consequences on prophylaxis and therapy of cholera and on bacterial identification, we have studied the genetic basis of cross-resistance to trimethoprim and O/129 of strains of Vibrio cholerae O1 independently isolated in Africa. Two classes of bacteria were found. In the first class, the strains were also resistant to ampicillin and kanamycin and to high levels of streptomycin by synthesis of a 3"- or 6-aminoglycoside phosphotransferase. The strains hybridized weakly with a Tn7 probe and all the resistance characters were transferable en bloc to Escherichia coli. The second class included strains which, in addition to trimethoprim and O/129, were resistant to moderate levels of streptomycin and spectinomycin by production of a 3",9-aminoglycoside-aminocyclitol adenylyltransferase. The resistance characters were not self-transferable to E. coli and the host strain hybridized strongly with Tn7. It therefore appears, that both plasmids and transposons are responsible for the dissemination of resistance to trimethoprim and O/129 in Vibrio.
Insights
Genetic elements like plasmids and transposons spread trimethoprim and O/129 resistance in Vibrio cholerae O1 strains. This study identified two classes of resistant bacteria, impacting cholera treatment and identification.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Antimicrobial resistance in Vibrio cholerae O1 is a significant public health concern, affecting cholera prophylaxis, therapy, and bacterial identification.
- Cross-resistance to trimethoprim and O/129 (a V. cholerae O1 specific agent) has important implications for treatment strategies.
Purpose of the Study:
- To investigate the genetic basis of trimethoprim and O/129 cross-resistance in Vibrio cholerae O1 strains isolated in Africa.
- To characterize the mechanisms and genetic elements responsible for the dissemination of these resistance traits.
Main Methods:
- Phenotypic characterization of resistance profiles (trimethoprim, O/129, ampicillin, kanamycin, streptomycin, spectinomycin).
- Enzymatic assays to identify resistance mechanisms (aminoglycoside phosphotransferase, adenylyltransferase).
- Genetic analysis including hybridization with Tn7 probe and intergeneric conjugation experiments with Escherichia coli.
Main Results:
- Two distinct classes of resistant Vibrio cholerae O1 strains were identified.
- Class 1 strains exhibited resistance to ampicillin, kanamycin, and high-level streptomycin via aminoglycoside phosphotransferase synthesis, with resistance transferable via plasmids and weak Tn7 hybridization.
- Class 2 strains showed resistance to moderate streptomycin and spectinomycin via adenylyltransferase production, with non-transferable resistance and strong Tn7 hybridization, suggesting transposon involvement.
Conclusions:
- Both plasmids and transposons play a role in the dissemination of trimethoprim and O/129 resistance in Vibrio.
- Understanding these genetic mechanisms is crucial for effective cholera control and antimicrobial stewardship.