In VitroActivities of CB-183,315, Vancomycin, and Metronidazole against 556 Strains of Clostridium difficile, 445 Other Intestinal Anaerobes, and 56 Enterobacteriaceae Species

Abstract

ABSTRACTMICs of CB-183,315, a novel lipopeptide antibiotic, vancomycin, and metronidazole were determined for intestinal anaerobes andEnterobacteriaceae. The MIC90s for Gram-negative anaerobes were >8,192, 8,192, and 4 μg/ml for CB-183,315, vancomycin, and metronidazole, respectively. AgainstEnterobacteriaceae, the MIC90s were >8,192 μg/ml, 1,024 μg/ml, and 1,024 μg/ml, respectively. The CB-183,315 MIC90forClostridium difficilewas 0.5 μg/ml. Its lack of activity against normal fecal organisms makes it a promising new agent for treatingC. difficile.