Plasmid-determined resistance to arsenic and antimony in Pseudomonas aeruginosa.

Resistance to arsenic salts in a Pseudomonas aeruginosa clinical isolate was shown to be determined by a 100 kb transferable plasmid. The resistance pattern included arsenate, arsenite, and antimonate ions. Arsenate and arsenite resistances were inducible by previous exposure of cultures to subinhibitory amounts of either of the two ions. Phosphate ions protected P. aeruginosa cells from the toxic effects of arsenate but did not alter arsenite toxicity.