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Macrolide resistance mechanisms in Gram-positive cocci.
1Department of Microbiology and Genetics, University Medical Centre, 1 Rue Michel Servet, CH-1211, Geneva, Switzerland. pechere@cmu.unige.ch
International Journal of Antimicrobial Agents
|September 28, 2001
Summary
Two main antibiotic resistance mechanisms exist in Gram-positive bacteria: erm genes causing high-level resistance and mefE genes enabling low-level macrolide efflux. Azithromycin effectively targets strains with mefE genes.
Area of Science:
- Microbiology
- Molecular Biology
- Pharmacology
Background:
- Gram-positive bacteria exhibit resistance to macrolide antibiotics through identified genetic mechanisms.
- Two primary resistance pathways involve ribosomal RNA modification and active antibiotic efflux.
Purpose of the Study:
- To elucidate the principal mechanisms of macrolide resistance in Gram-positive bacteria.
- To differentiate the clinical significance and resistance levels associated with specific macrolide resistance genes.
Main Methods:
- Analysis of genetic determinants of macrolide resistance, specifically erm and mefE genes.
- Evaluation of bacterial protein synthesis inhibition and antibiotic efflux mechanisms.
- Assessment of azithromycin efficacy against bacteria harboring mefE genes.
Main Results:
- The erm gene confers high-level macrolide resistance by altering ribosomal RNA structure, preventing antibiotic binding.
- The mefE gene mediates low-level macrolide resistance through an efflux mechanism.
- Azithromycin demonstrated efficacy in eradicating mefE-carrying bacterial strains due to its concentration at infection sites.
Conclusions:
- Erm-mediated ribosomal modification and mefE-mediated efflux are key macrolide resistance mechanisms in Gram-positive bacteria.
- Resistance levels vary significantly between these two mechanisms.
- Azithromycin holds therapeutic potential against specific macrolide-resistant bacterial infections.