Resistance to metals by Pseudomonas aeruginosa clinical isolates.

The susceptibility of 326 clinical isolates of Pseudomonas aeruginosa to four metals was determined by agar dilution tests. Metal resistance was shown by 36% of the total isolates. The frequencies of resistance to individual ions were: mercuric, 31%; tellurite, 12%; arsenate, 10%; and chromate, 3%. The most frequent pattern was that of resistance to mercuric ions alone followed by mercury resistance associated with either tellurite, arsenate, or both. Resistance to more than one metal was found in 44% of metal-resistant isolates. The resistance to antibiotics was more frequent among metal-resistant isolates that in metal-sensitive isolates.