Outer membrane permeability and beta-lactamase content in Pseudomonas maltophilia clinical isolates and laboratory mutants.

Low outer-membrane permeability appears to be responsible for the generally high degree of antibiotic resistance of Pseudomonas maltophilia. Constitutive overproduction of beta-lactamases affects the sensitivity of these bacteria only to those beta-lactam antibiotics that are hydrolyzed by strain-specific beta-lactamases and that do not efficiently induce these enzymes in inducible strains.