Comparative in vitro activity of ertapenem and 11 other antimicrobial agents against aerobic and anaerobic pathogens isolated from skin and soft tissue animal and human bite wound infections

We studied the comparative in vitro activity of ertapenem, a new carbapenem , against 240 aerobic and 180 anaerobic recent clinical bite isolates using an agar dilution method and an inoculum of 10(4) cfu/spot for aerobes and 10(5) cfu/spot for anaerobes. Ertapenem inhibited 410/420 (98%) of the isol ates tested at less than or equal to4 mg/L with only 4/5 Campylobacter grac ilis and 1/3 Campylobacter rectus strains requiring;greater than or equal t o 16 mg/L for inhibition. Ertapenem was only moderately active (MIC 8 mg/L) against 4/6 Enterococcus faecalis and 1/11 Staphylococcus epidermidis stra ins. All Pasteurella multocida, Pasteurella septica, Pasteurella canis, Pas teurella dagmatis, Moraxella spp. and EF-4 isolates were inhibited at less than or equal to0.01 5 mg/L. MIC(90)s for other aerobic genera and species were as follows: Corynebacterium spp., 4 mg/L; Staphylococcus aureus, 0.25 mg/L; Staphylococcus epidermidis, 4 mg/L; other coagulase-negative staphylo cocci, 0.25 mg/L; Streptococcus milleri group, 0.5 mg/L; Eikenella corroden s, 0.03 mg/L; and Bergeyella zoohelcum, 0.5 mg/L. For anaerobes the range o f MiCs and MIC90s were: Prevotella ssp., less than or equal to0.015-0.5, 0. 125 mg/L; Porphyromonas spp., less than or equal to0.015-0.03, less than or equal to0.015 mg/L; Fusobacterium spp., 0.015-0.125, 0.03 mg/L; Bacteroide s tectum, 0.03-0.125, 0.125 mg/L; and Peptostreptococcus spp., 0.01-2, 1 mg /L. Ertapenem showed excellent potency against the full range of animal and human bite wound pathogens.