Differential release of endotoxin from Pseudomonas aeruginosa treated with beta-lactam antibiotics and its effect on the lethal activity.

The relationship between the level of endotoxin released from Pseudomonas aeruginosa by exposure to beta-lactam antibiotics and the lethal activity against D-galactosamine (D-GalN)-sensitized mice was examined. In vitro treatment of P. aeruginosa with imipenem (IPM) exclusively caused low-level release of free endotoxin, which was not lethal for D-GalN-sensitized mice. Treatment with other beta-lactam antibiotics, such as ceftazidime (CAZ), meropenem (MEPM) and cefozopran (CZOP) caused high-level release of free endotoxin and it exhibited the lethal action against D-GalN-sensitized mice. This study demonstrated close association of free endotoxin released by antibiotic treatment with the lethal activity.