Fig. 1

Frequency of asymptomatic carriage of toxigenic Clostridium difficile in hospitalized patients, stratified by antibiotic treatment classification. Based upon a modification of the classification scheme of Owens et al. [1], antibiotics on the formulary that were classified as having inhibitory activity against C. difficile included ampicillin, amoxicillin, linezolid, metronidazole, imipenem, meropenem, piperacillin/tazobactam, tigecycline, and tetracyclines. Antibiotics on the formulary that were considered to have poor activity included cephalosporins, ciprofloxacin, and trimethoprim/sulfamethoxazole. Moxifloxacin was classified as having variable activity against C. difficile