Outer membrane proteins in a carbenicillin-resistant strain of Pseudomonas aeruginosa

The outer membrane of a clinical isolate of Pseudomonas aeruginosa sensitive to carbenicillin, and its derivative adapted to grow in the presence of carbenicillin were analysed by polyacrylamide gel electrophoresis. The lack of beta-lactamase activity showed that the resistance of the adapted strain was not due to hydrolysis of carbenicillin. The appearance of several outer membrane proteins almost exclusively in the resistant strain supports the view of altered cell envelope properties in this strain.