Edetate disodium-mediated chloramphenicol resistance in Pseudomonas cepacia

The presence of edetate disodium decreased the susceptibility of a particular strain of Pseudomonas cepacia to chloramphenicol. The mechanism of this edetate disodium effect, which may be unique to this strain, remains obscure. Tests showed no enzymatic destruction by the microorganism of the chloramphenicol nor any chemical complexation of the antibiotic by the salt. The possibility does exist that edetate disodium alters the cell envelope or cytoplasmic membrane so as to block the transport of chloramphenicol to its site of action within the cell. This possibility is now under investigation.