Modified time-kill assay against multidrug-resistant Enterococcus faecium with novel antimicrobial combinations.

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Multidrug-resistant Enterococcus faecium poses a significant threat.
• Limited effective treatment options exist for these infections.
• Evaluating antibiotic combinations is crucial for treatment strategies.

Purpose of the Study:

• To compare the in-vitro activity of chloramphenicol and quinopristin/dalfopristin in combination with vancomycin, ampicillin, or gentamicin against multidrug-resistant Enterococcus faecium.
• To assess the efficacy of a modified time-kill assay that simulates in-vivo conditions.

Main Methods:

• Utilized a modified time-kill assay with specific centrifugation and resuspension steps.
• Simulated steady-state serum concentrations of antibiotics.
• Tested combinations of chloramphenicol and quinopristin/dalfopristin with vancomycin, ampicillin, or gentamicin.

Main Results:

• None of the tested antibiotic agents, alone or in combination, demonstrated bactericidal activity.
• No synergistic effects were observed between the antibiotic combinations.
• The modified assay provided a closer simulation of in-vivo conditions.

Conclusions:

• The tested antibiotic combinations were not effective against multidrug-resistant Enterococcus faecium in this in-vitro model.
• The modified time-kill assay may offer a more relevant qualitative assessment of antimicrobial agent interactions.
• Further research is needed to identify effective treatment strategies for multidrug-resistant Enterococcus faecium infections.