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Published on: February 10, 2011
Is ampicillin plus cephalosporins a therapeutic option for Ampicillin-Susceptible Enterococcus faecium?
Paula Bierge1,2, Inmaculada Gómez-Sánchez1,2, Cristina Garcia de la Mària3
1Laboratori de Recerca en Microbiologia i Malalties Infeccioses, Hospital Universitari Parc Taulí, Institut d'Investigació i Innovació Parc Taulí (I3PT-CERCA), Universitat Autònoma de Barcelona, Sabadell, Spain.
Objectives:
Enterococcus faecium, a significant hospital associated pathogen, poses substantial treatment challenges. While combinations of ampicillin with cephalosporins are first-line therapies to treat Enterococcus faecalis high-mortality-rates infections, their efficacy against ampicillin-susceptible E. faecium (ASEfm) is less clear. This study evaluates the effectiveness of combining ampicillin with ceftriaxone or ceftaroline against ASEfm strains.
Methods:
Ten ASEfm bloodstream isolates from complicated infections were analyzed. Susceptibility to several antibiotics, including ceftriaxone, ceftaroline, and cefotaxime, was determined using standard methods. Time-kill assays were conducted to assess the synergistic and additive effects of ampicillin in combination with ceftriaxone or ceftaroline.
Results:
Time-kill studies revealed that ampicillin combined with ceftaroline demonstrated synergistic and/or additive effects in 7 out of 10 strains analyzed. In contrast, ampicillin combined with ceftriaxone showed less pronounced synergy, with only 3 out of 10 strains exhibiting synergistic and/or additive effects.
Conclusions:
Our findings indicate that ampicillin combined with ceftaroline, or ceftriaxone provides synergistic activity against some but not all ASEfm clinical isolates. The observed synergy suggests that these combinations could offer a potential therapeutic option for challenging ASEfm infections.
Insights
Ampicillin combined with ceftaroline showed synergistic effects against most ampicillin-susceptible Enterococcus faecium strains. This combination may offer a new treatment option for difficult-to-treat hospital-associated infections.
Area of Science:
- Infectious Diseases
- Microbiology
- Pharmacology
Background:
- Enterococcus faecium is a major hospital-associated pathogen.
- Treatment of Enterococcus faecium infections is challenging.
- Efficacy of ampicillin-cephalosporin combinations against ampicillin-susceptible E. faecium (ASEfm) is not well-defined.
Purpose of the Study:
- To evaluate the effectiveness of combining ampicillin with ceftriaxone or ceftaroline against ASEfm strains.
- To determine synergistic and additive effects of these antibiotic combinations.
Main Methods:
- Analysis of ten ASEfm bloodstream isolates from complicated infections.
- Antibiotic susceptibility testing for ceftriaxone, ceftaroline, and cefotaxime.
- Time-kill assays to assess synergistic and additive effects of ampicillin combined with ceftriaxone or ceftaroline.
Main Results:
- Ampicillin plus ceftaroline demonstrated synergistic/additive effects in 70% (7/10) of ASEfm strains.
- Ampicillin plus ceftriaxone showed less pronounced synergy, with effects in 30% (3/10) of strains.
Conclusions:
- Ampicillin combined with ceftaroline or ceftriaxone shows synergistic activity against some ASEfm clinical isolates.
- These combinations represent a potential therapeutic strategy for challenging ASEfm infections.
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