Chloramphenicol Acetyltransferases Determined by R Plasmids from Gram-negative Bacteria

Abstract
Summary: The mechanism of resistance to chloramphenicol specified by 18 plasmids from Gram-negative bacteria representing different incompatibility groups was investigated. Most determined the drug-inactivating enzyme chloramphenicol acetyltransferase. The enzymes were purified and their properties were compared with those of the previously characterized enzyme types specified by R429 (type I), s-a (type II) and R387 (type III). The type I enzyme was determined by plasmids representing incompatibility groups FII, C, S, I, H, L, O and Com9. Plasmids from incompatibility groups K, Iγ and the A-C complex specified the type III enzyme, while elements representing incompatibility groups V and W determined the type II variant.