Objective To observe the release of endotoxin from
Pseudomonas aeruginosa after incubated with single or combined
antibiotics
and to explore possible mechanisms. Methods Cultures containing
Pseudomonas aeruginosa were treated with six kinds of antibiotics as Piperacillin/Tazobactam (PIP/TAZ), Cefoperazone (CPZ), Imipenem/Cilastatin (IMP/CIL), Meropenem (MEM), Ciprofloxacin (CIP), Amikacin (AMK) single or combined in concentrations of 0.5 MIC. The changes of the CFU counting, morphology and the levels of endotoxin in the supernatants were observed at different time points. Results Different antibiotics induce endotoxin release from Pseudomonas
Aeruginosa during the change of morphological features and the killing of bacterial. All of the six kinds of single antibiotics could kill the bacterial with similar efficacy. A significant decrease in bacterial quantity and endotoxin release was noticed in combination of two antibiotics as compared to the single antibiotic groups. PIP/TAZ, MEM, CIP groups could convert the bacteria into filamentous shape with significant release of endotoxin, while IMP/CIL group could made the bacteria to spherical shape with less release of endotoxin as compared to the control. Antibiotics combined and CPZ group could induce lysis of bacteria with less LPS. Along with the prolongation of the action time, the endotoxin release increased. Conclusion All of the six kinds of antibiotics single or combined could induce Pseudomonas aeruginosa to release different amounts of endotoxin, which was correlated to the antibiotics classes, action time and the bacterial morphological changes. This result suggested an important strategy in antibiotic chemotherapy.