Related Experiment Videos
Evolution of multiple-antibiotic-resistance plasmids mediated by transposable plasmid deoxyribonucleic acid sequences
Abstract:
Two plasmid deoxyribonucleic acid sequences mediating multiple antibiotic resistance transposed in vivo between coexisting plasmids in clinical isolates of Serratia marcescens. This event resulted in the evolution of a transferable multiresistance plasmid. Both sequences, designated in Tn1699 and Tn1700, were flanked by inverted deoxyribonucleic acid repetitions and could transpose between replicons independently of the Excherichia coli recA gene function. Tn1699 and Tn1700 mediated ampicillin, carbenicillin, kanamycin, and gentamicin resistance but differed in the type of gentamicin-acetyltransferase enzymes that they encoded. The structural genes for these enzymes share a great deal of polynucleotide sequence similarity despite their phenotypic differences. The transposition of Tn1699 and Tn1700 to coresident transferable plasmids has contributed to the dissemination of antibiotic resistance among other gram-negative bacteria. These organisms have recently caused nosocomial infections in epidemic proportions.
Insights
Two novel DNA sequences, Tn1699 and Tn1700, facilitate the transfer of antibiotic resistance genes between plasmids in Serratia marcescens. This promotes the spread of antimicrobial resistance in clinically significant bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Antibiotic resistance is a growing global health threat, particularly in hospital-acquired infections.
- Plasmids play a crucial role in the dissemination of antimicrobial resistance genes among bacteria.
- Serratia marcescens is an opportunistic pathogen frequently implicated in nosocomial infections.
Purpose of the Study:
- To identify and characterize the deoxyribonucleic acid (DNA) sequences responsible for mediating antibiotic resistance transfer in Serratia marcescens.
- To investigate the mechanism of transposition and evolution of multiresistance plasmids.
Main Methods:
- Analysis of plasmid DNA sequences from clinical isolates of Serratia marcescens.
- Identification of novel transposable elements (Tn1699 and Tn1700) mediating antibiotic resistance.
- Investigation of transposition capabilities and dependence on host factors (e.g., Escherichia coli recA gene).
Main Results:
- Two distinct DNA sequences, Tn1699 and Tn1700, were identified, each flanked by inverted repeats.
- These sequences mediate resistance to ampicillin, carbenicillin, kanamycin, and gentamicin.
- Tn1699 and Tn1700 transpose independently of the Escherichia coli recA gene function.
- The structural genes for gentamicin resistance enzymes show high sequence similarity despite phenotypic differences.
Conclusions:
- The transposition of Tn1699 and Tn1700 between plasmids contributes significantly to the evolution and spread of transferable multiresistance plasmids.
- This mechanism facilitates the dissemination of antibiotic resistance among gram-negative bacteria, exacerbating the problem of nosocomial infections.