In vitro activity of LY281389 and comparison with erythromycin and oral beta-lactams

LY281389 is a new 14-member ring macrolide which is presently being developed for possible clinical use against bacterial infections. We compared the in vitro activity of LY281389 with erythromycin, ampicillin, augmentin and cephalexin against 610 clinical isolates. The new drug inhibited 97 and 11% of methicillin-sensitive and methicillin-resistant Staphylococcus aureus isolates, respectively, 59% of coagulase-negative staphylococci, 63% of enterococci and 74% of Haemophilus influenzae. All the 171 isolates of Streptococcus Lancefield group A, group B and Streptococcus pneumoniae were susceptible to LY281389 at MIC values ranging between 0.03 and 0.24 micrograms/ml. In vitro activity of LY281389 against the bacteria tested was comparable to that of erythromycin.