In-vitro study of the synergy between beta-lactam antibiotics and glycopeptides against enterococci.
The synergy between glycopeptides and beta-lactams was studied using different techniques such as broth macrodilution, killing curves and agar dilution combined with agar diffusion. Two glycopeptide-resistant enterococci isolated from different clinical samples were used. Results showed different effects with significant changes in MICs. Antibacterial activity was related to the concentration of glycopeptide and beta-lactam for Enterococcus faecalis 8253, while for Enterococcus faecium 8072 a paradoxical effect was observed. With this strain, the best synergic effect was detected at teicoplanin concentrations of 1-4 mg/L, but antibacterial activity was reduced at concentrations of 8, 16 and 32 mg/L. No synergic effect was observed with vancomycin. The combination of agar dilution with agar diffusion techniques may constitute a simple method for routine detection of synergic effects between glycopeptides and beta-lactams.
Ravizzola
G
G
Institute of Microbiology, University of Brescia, Spedali Civili, Italy.
Cabibbo
E
E
Peroni
L
L
Longo
M
M
Pollara
P C
PC
Corulli
M
M
Pizzi
R
R
Dima
F
F
Fallacara
C
C
Turano
A
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002511:Cephalosporins / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D016983:Enterococcus / Q000187:drug effects*; D013293:Enterococcus faecalis / Q000187:drug effects; D016984:Enterococcus faecium / Q000187:drug effects; D006020:Glycopeptides / Q000494:pharmacology*; D015378:Imipenem / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D010878:Piperacillin / Q000494:pharmacology; D017334:Teicoplanin / Q000494:pharmacology; D014640:Vancomycin / Q000494:pharmacology; D047090:beta-Lactams / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D006020:Glycopeptides; D047090:beta-Lactams; D017334:Teicoplanin; D014640:Vancomycin; D015378:Imipenem; D010878:Piperacillin