5-Bromo-6-chloro-3-indolyl b-D-glucuronide (5BCIG) is an antibiotic that inhibits bacterial growth by binding to the DNA gyrase and topoisomerase IV, which are enzymes that maintain the integrity of bacterial DNA. 5BCIG is detectable in tissues, and quantified in blood. It encodes a protein to the cell cytoplasm. The sensitivity of 5BCIG against clostridium perfringens was found to be 10 times higher than that of penicillin G or erythromycin. 5BCIG has optimal activity against clostridium perfringens when expressed functionally as a polypeptide.