Antimicrobial activity of cefditoren tested against contemporary (2004–2006) isolates of Haemophilus influenzae and Moraxella catarrhalis responsible for community-acquired respiratory tract infections in the United States

Among orally administered cephalosporins, aminopenicillins (±clavulanate), and macrolides, cefditoren was the most potent agent against Haemophilus influenzae (MIC50/90, ≤0.008/0.03 μg/mL; 316 isolates including 100 β-lactamase–positive and 10 β-lactamase–negative ampicillin-resistant [BLNAR]) and was 32-, 64-, and 512-fold more potent than cefdinir, cefuroxime, and cefprozil, respectively. Cefditoren (MIC50, 0.03 μg/mL) was also ≥32-fold more active against BLNAR phenotypes, although newer macrolides provided complete coverage against these strains. All Moraxella catarrhalis isolates were inhibited by cefditoren (0.5 μg/mL), including β-lactamase producers (MIC50, 0.12 vs ≤0.008 μg/mL). Cefditoren retains potent activity against respiratory tract isolates in the United States, including those with resistance phenotypes.