GAR-936, a novel
glycylcycline, was investigated with a rat model of experimental
endocarditis. It was compared with
vancomycin against both
vancomycin-susceptible and -resistant Enterococcus faecalis and methicillin-resistant Staphylococcus aureus.
GAR-936 exhibited the lowest MICs (</=0.12 microgram/ml) in vitro against each of the isolates tested.
Endocarditis was established by placement of a
catheter across the aortic valve, followed by
intravenous injection of 10(6) CFU of bacteria 48 h later. Treatment with
GAR-936 or
vancomycin was initiated 24 to 36 h after
bacterial infection and administered subcutaneously twice a day for 3 days at ascending doses.
GAR-936 reduced bacterial vegetation titers by >2 log(10) CFU, compared to those in untreated controls, for both
vancomycin-susceptible and -resistant (VanA and VanB) E. faecalis strains and >4 log(10) CFU for a methicillin-resistant S. aureus isolate. The
glycylcycline was more efficacious at a lower administered dose in the rat model of
endocarditis than was
vancomycin. The efficacy of
GAR-936 in this model was apparently not enhanced by
a factor in rat serum, as was observed for
vancomycin with a time-kill curve. The results of this study demonstrate the therapeutic potential of
GAR-936 for the treatment of enterococcal and
staphylococcal infections and warrant further investigation.