Clinical glycopeptide-intermediate staphylococci tested against arbekacin, daptomycin, and tigecycline

We examined the activity of arbekacin, daptomycin, tigecycline, and vancomycin against various Staphylococci isolates with glycopeptide-intermediate (n = 25) and heterogeneous susceptibilities (n = 22) (GISS and hGISS). The minimum inhibitory concentrations (MIC) of each antimicrobial was evaluated in time-kill experiments by using 4 randomly selected GISS isolates tested at 2 and 4 times their respective MIC. The MIC(90) microg/mL ranges for arbekacin, daptomycin, tigecycline, and vancomycin were 2 (0.25-4), 1 (0.0625-2), 0.5 (0.0625-2), and 8 (4-8), respectively. Time kill at 2 times the MIC demonstrated a mean log(10) colony forming units (CFU)/mL change of -2.98 +/- 0.708, -3.6 +/- 0.509, -2.48 +/- 0.647, and +1.14 +/- 0.1 arbekacin, daptomycin, tigecycline, and vancomycin, respectively. At 4 times the MIC, significant activity for all compounds was noted with a log(10) CFU/mL decrease range from 3.68 to 2.74 +/- 0.66. Overall, all the antimicrobials tested (with the exception of vancomycin) exhibited significant in vitro activity against GISS. These compounds may offer therapeutic options for the treatment of GISS.