Efficacy of tigecyclin vs. vancomycin in ampicillin- and gentamicin-resistant E. faecium experimental endocarditis

Abstract number: R2255

Vryonis E., Perivolioti E., Fanourgiakis P., Platsouka E., Samarkos M., Katsimpoulas M., Balafas E., Kostomitsopoulos N., Karagianakos P., Paniara O., Skoutelis A.

Objectives: Tigecyclin is the first available glycycycline. It is a new drug exhibiting broad-spectrum activity against aerobic and anaerobic bacteria including multidrug resistant Gram-positive and Gram-negative pathogens.

The aim of this study was to evaluate the efficacy of tigecyclin compared to vancomycin in an animal model of experimental endocarditis due to an ampicillin (AMP) & gentamicin (GEN) resistant and tigecyclin glycopeptides susceptible clinical isolate of Enterococcus faecium.

Methods: We used a rabbit model of left sided experimental endocarditis. One day after the insertion and fixation of a polyethylene catheter into the left ventricle, animals were inoculated with E. faecium. Thirty-six hours later they were randomly assigned to a control group (C) and groups receiving intravenous tigecycline 7 mg/kg/q12 h x 5 days (T) or intravenous vancomycin 50 mg/kg/q12 h x 5 days (V). At the end of treatment all animals were sacrificed. Therapy response was determined by blood cultures and quantitative (log10 cfu/gr of tissue) cultures of aortic valve vegetations, liver, spleen, kidney and brain.

Results: The results obtained of the different therapeutics groups are expressed in the Table.

Conclusions: Although both regiments reduce significantly the bacterial count per gram of vegetations, treatment with V was found to be more potent than QD. Also animals treated with V had lower bacterial counts per gram of liver, brain and spleen tissue.