Comparative In Vitro Activities of ABT-773 against Aerobic and Anaerobic Pathogens Isolated from Skin and Soft-Tissue Animal and Human Bite Wound Infections

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Abstract
We studied the comparative in vitro activities of ABT-773, a new ketolide, against 268 aerobic and 148 anaerobic recent isolates from clinical bites using an agar dilution method and inocula of 10 4 CFU/spot for aerobes and 10 5 CFU for anaerobes. The following are the MIC ranges and MICs at which 90% of isolates are inhibited (MIC 90 s) of ABT-773 for various isolates, respectively: Pasteurella multocida and Pasteurella septica , 0.125 to 2 and 1 μg/ml; other Pasteurella species, 0.125 to 1 and 0.5 μg/ml; Corynebacterium spp., 0.015 to 0.06 and 0.015 μg/ml; Staphylococcus aureus , 0.03 to 0.06 and 0.06 μg/ml; coagulase-negative staphylococci, 0.015 to >32 and 32 μg/ml; streptococci, 0.015 to 0.03 and 0.03 μg/ml; Eikenella corrodens , 0.25 to 1 and 1 μg/ml; and Bergeyella zoohelcum , 0.03 to 0.25 and 0.06 μg/ml. For anaerobes the MIC ranges and MIC 90 s of ABT-773 were as follows, respectively: Prevotella heparinolytica , 0.06 to 0.125 and 0.125 μg/ml; Prevotella spp., 0.015 to 0.125 and 0.06 μg/ml; Porphyromonas spp., 0.015 to 0.03 and 0.015 μg/ml; Fusobacterium nucleatum , 0.5 to 8 and 8 μg/ml; other Fusobacterium spp., 0.015 to 8 and 0.5 μg/ml; Bacteroides tectum , 0.015 to 0.5 and 0.06 μg/ml; and Peptostreptococcus spp., 0.015 to 0.25 and 0.03 μg/ml. ABT-773 was more active than all macrolides tested against S. aureus , E. corrodens , and anaerobes, but all compounds were poorly active against F. nucleatum . The activity of ABT-773 was within 1 dilution of that of azithromycin against Pasteurella spp., and ABT-773 was four- to eightfold more active than clarithromycin against Pasteurella spp. ABT-773 may offer a therapeutic alternative for bite wound infections.