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In vitro antimicrobial susceptibility of glycopeptide-resistant enterococci
C Freeman1, A Robinson, B Cooper
1Department of Pharmacy, Hartford Hospital, Connecticut, USA.
Abstract:
The results of susceptibility testing of 48 phenotyped strains of glycopeptide antibiotic-resistant enterococci are reported. Minimum inhibitory and bactericidal concentrations (MICs and MBCs) were determined for 27 vanA, 17 vanB, and 4 vanC strains. Antibiotics exhibiting the greatest activity included novobiocin (MIC90 = 8 micrograms/ml and MBC90 = 32 micrograms/ml), ramoplanin (MIC90 = 2 micrograms/ml and MBC90 = 4 micrograms/ml), and the streptogramin RP59500 (MIC90 = 4 micrograms/ml and MBC90 = 32 micrograms/ml). These antibiotics warrant further investigation as potentially useful agents, either alone or in combination, for treating enterococcal infections.
Insights
Novobiocin, ramoplanin, and streptogramin RP59500 show promise against antibiotic-resistant enterococci. Further research is recommended for these agents in treating enterococcal infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Enterococci are significant nosocomial pathogens.
- Glycopeptide antibiotic resistance in enterococci (e.g., vanA, vanB, vanC strains) poses a therapeutic challenge.
- Effective treatment options for resistant enterococcal infections are limited.
Purpose of the Study:
- To evaluate the in vitro activity of various antibiotics against phenotyped, glycopeptide-resistant enterococcal strains.
- To identify potential alternative therapeutic agents for treating infections caused by these resistant bacteria.
Main Methods:
- Susceptibility testing was performed on 48 phenotyped strains of glycopeptide-resistant enterococci.
- Minimum Inhibitory Concentrations (MICs) and Minimum Bactericidal Concentrations (MBCs) were determined for selected antibiotics.
- Strains were categorized based on their resistance mechanisms (vanA, vanB, vanC).
Main Results:
- Novobiocin demonstrated significant activity with MIC90 of 8 µg/ml and MBC90 of 32 µg/ml.
- Ramoplanin exhibited potent activity, with MIC90 of 2 µg/ml and MBC90 of 4 µg/ml.
- The streptogramin RP59500 showed promising results, with MIC90 of 4 µg/ml and MBC90 of 32 µg/ml.
Conclusions:
- Novobiocin, ramoplanin, and RP59500 are effective in vitro against glycopeptide-resistant enterococci.
- These antibiotics represent potential candidates for further investigation in treating enterococcal infections.
- Combination therapy might also be a viable strategy for managing these resistant infections.