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[Transmission of the R-plasmids and expression of their genes in Proteus mirabilis]
Abstract:
Resistance markers to individual antibiotics are transmitted in E. coli with the same frequency in the shape of a uniform linkage group, and in Proteus mirabilis--with a different one. Possibly in Proteus mirabilis plasmide R6 dissociated, this being expressed in a different incidence of transconjugates, characterized by a different set of antibiotic resistance genes. Tetracyclin resistance gene can be transmitted in P. mirabilis without being bound with other resistance determinants and with the functioning Tra-operon. The expression of individual antibiotic resistance genes of plasmide R6 in P. mirabilis differed, i.e. tetracycline resistance was inducible, and to kanamycin and chloramphenicol--constitutional. The level of expression of the gene controlling the tetracycline resistance was in noninduced condition in P. mirabilis, lower than in E. coli, P. mirabilis containing no R-factor possessed an inducible resistance mechanism to tetracycline, as in case of P. mirabilis strains containing R-factors.
Insights
Antibiotic resistance genes transmit differently between E. coli and Proteus mirabilis. Proteus mirabilis shows unique tetracycline resistance gene transmission and expression patterns, differing from E. coli.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Antibiotic resistance gene transmission is crucial in bacterial evolution.
- Understanding gene linkage and expression differences between bacterial species is vital for combating resistance.
Purpose of the Study:
- To investigate the transmission patterns and expression of antibiotic resistance genes in Proteus mirabilis compared to E. coli.
- To analyze the role of plasmid R6 in mediating these differences.
Main Methods:
- Conjugation experiments to assess gene transmission frequencies.
- Analysis of transconjugates for antibiotic resistance gene profiles.
- Gene expression studies under induced and non-induced conditions.
Main Results:
- Proteus mirabilis exhibits different linkage group patterns for antibiotic resistance compared to E. coli.
- The tetracycline resistance gene in P. mirabilis can transmit independently and shows inducible expression.
- Expression levels of tetracycline resistance genes are lower in P. mirabilis than in E. coli.
Conclusions:
- Plasmid R6 may dissociate in P. mirabilis, leading to varied resistance gene combinations and expression.
- P. mirabilis possesses an intrinsic inducible resistance mechanism to tetracycline, independent of R-factors.