丁胺卡那霉素和头孢曲松诱导细菌释放内毒素的实验研究

An empirical study on amikacin and ceftriaxone-induced release of endotoxin from bacterium

目的探讨丁胺卡那霉素和头孢曲松在不同浓度和时间点诱导产ESBLs和非产ESBLs大肠埃希菌释放内毒素的量-效关系。方法常规方法分离、培养和鉴定产ESBLs和非产ESBLs大肠埃希菌;显色基质鲎试剂(微板法)分别测定0.1、0.5、1.0和10MIC的药物作用细菌2、4、8h后内毒素的释放量(查对内毒素标准曲线)以及细菌形态的变化。结果丁胺卡那霉素和头孢曲松诱导非产ESBLs大肠埃希菌以及丁胺卡那霉素在0.5MIC浓度范围内诱导产ESBLs大肠埃希菌释放的内毒素的量随着药物浓度和培养时间的增加而增加,而>0.5MIC浓度时释放的内毒素的量随药物浓度增加而显著减少。头孢曲松在10MIC范围内诱导产ESBLs大肠埃希菌释放的内毒素的量随药物浓度的增加而缓慢增加,在10MIC时释放量最大。不同作用时间内毒素释放量的顺序为8h>4h>2h。丁胺卡那霉素引起细菌从球杆状变为长杆状,而头孢曲松则引起细菌从杆状变为长链状或长丝状。结论头孢曲松诱导大肠埃希菌释放内毒素的能力显著强于丁胺卡那霉素,且引起细菌形态的变化更为显著。临床上在治疗感染性疾病时,应加大首次用药剂量,达到有效杀菌浓度而非抑菌浓度,以达到更好的临床治疗效果。

Objective To discuss amikacin and ceftriaxone-induced release of ESBLs and non-ESBLs from Escherichia coli and its relationship of endotoxic content-potency at different concentration and different time. Methods ESBLs and non-ESBLs-produced Escherichia coli were isolated, cultivated and identified by routine method. The releasing endotoxin contents at 0.1 MIC （ minimum inhibitory con- centrations）, 0. 5 MIC, 1.0 MIC, 10 MIC after 2h, 4h, 8h of bacterium handling （find endotoxic standard curve） were measured respectively by colouration-basilaris-substantia tachypleus amebocyte lysate （mini-slab method） and the morphologic changes of bacteria were observed. Results The released endotoxic content of amikacinor ceftriaxone-induced non-ESBLs from Escherichia coli and amikacininduced ESBLs from Escherichia coli increased with antibiotic concentration and cultural time within the range of 0.5 MIC, but endotoxic content significantly diminished with increased antibiotic concentration when antibiotic concentration exceed 0.5 MIC. The released endotoxic content of ceftriaxone-induced ESBLs from Escherichia coli increased slowly with antibiotic concentration within the range of 10 MIC concentration. The released endotoxic content reached maximum at 10 MIC. The released endotoxic content at different bacterium concentrations was as the following oeder： 0.5 MIC 〉 1.0 MIC 〉 10 MIC. The released endotoxic content at different time was as the following order：8h 〉 4h 〉 2h. The shape of bacterium was changed by amikacin from sphero-rhabditiform to dolicho-rhabditiform, while by ceftriaxone changed from rhabditiform to long-chain-form or filament-form. Conclusion The capability of ceftriaxone-induced release of endotoxin from Escherichia coli is significantly stronger than that of amikacin, and the morphologic changes of bacteria caused by ceftriaxone were more significant. For Clinical treatmentg of infectious diseases the first dosage of medication should increase to reach the effective bactericidal concentration but not the bacteriostasis concentration in order to receive better therapeutic effects.