An Experimental Study On The Endotoxin Release Of Acinetobacter Baumannii Induced By Different Antibiotics

Objective: To study the LPS release of acinetobacter baumannii afterincubated with single or combined antibiotics in different concentration anddifferent time,and the relationship between LPS release and morphologicalchanges of bacteria.Methods: Selected the common clinical GNB infection of Acinetobacterbaumannii, Standard strains and drug-resistant strains were exposed tocefoperazone sulbactam(CPZ/SBT),Imipenem and CilastatinSodium(IPMP/CIL), and amikacin(AMK) at0.5MIC,1MIC,10MICand100MIC. Samples（1ml）were obtained at0h,2h,4h,6h,8h after bacteriaexposing to antibiotics. Measure fractional inhibitory concentration ofCPZ/SBT and IPMP/CIL associate with AMK, Standard strains anddrug-resistant strains were exposed to IPMP/CIL and AMK at1FIC. Samples（1ml）were obtained at0h,2h,4h,6h,8h after bacteria exposing toantibiotics.LPS release was measured by Tachypleus amebocyte lysateTest(TAL Test). The culture without antibiotic acted as a control, brothwithout drug and bacteria was a blank tube.Results:1Different types antibiotics effect on bacteria LPSWhen Acinetobacter baumannii standard bacteria were treated with threetypes of antibiotics at0.5MIC, LPS release is: IPMP/CIL> CPZ/SBT> AMK;at1MIC, LPS release in0h,2h is: IPMP/CIL> CPZ/SBT> AMK,in4h,6h,8his: CPZ/SBT>IPMP/CIL> AMK； at10MIC, LPS release is: CPZ/SBT>IPMP/CIL> AMK.2Different concentrations of antibiotics effect on bacteria LPSWhen bacteria were treated with CPZ/SBT and IPMP/CIL,with theincrease of concentration,the LPS release were reduced. When Acinetobacter baumannii were treated with AMK, at0.5MIC、1MIC、10MIC lower LPS release were induced than at0.5MIC.3Incubation time of antibiotics effect on bacteria LPSWith the prolongation of incubation time, antibiotics induced the bacteriaLPS release gradually increased.4Combined use of antimicrobials effect on bacteris LPSWhen Acinetobacter baumannii standard bacteria were treated withcombination of three drugs at1MIC, LPS release is: CPZ/SBT>IPMP/CIL> CPZ/SBT+AMK> IPMP/CIL+AMK>AMK.Conclusions：1When three kinds of antibiotics acted on Acinetobacter baumannii,CPZ/SBT and IPMP/CIL induced more LPS release than AMK. when threekinds of antibiotics were combined, the minimum LPS release were induced.2CPZ/SBT, IPMP/CIL and AMK could induce A. baumannii to releasedifferent levels of LPS. LPS released from bacteria was related to types ofantibiotics, concentrations and time of incubation.3When AMK acted on Acinetobacter baumannii,the minimum LPS releasewere induced,but now clinical isolated bacteria to AMK resistant generally.CPZ/SBT or IPMP/CIL and AMK combination to achieve good antibacterialeffect,clinical anti-infection treatment should be as soon as possible joint useof antibacterial and can induce bacteria relesased less LPS.