Chromosomal beta-lactamase is packaged into membrane vesicles and secretedfrom Pseudomonas aeruginosa

Membrane vesicles were isolated from one beta-lactam-sensitive and three be ta-lactam-resistant Pseudomonas aeruginosa clinical isolates from patients with cystic fibrosis. The presence of the chromosomally encoded beta-lactam ase in the membrane vesicles was shown by electron microscopy and enzymatic studies. This is the first report of extracellular secretion of beta-lacta mase in P. aeruginosa and it seems that the enzyme is packaged into membran e vesicles.