摘要:
目的:观察比较头孢噻肟(CTX)对细菌广谱及超广谱β-内酰胺酶的稳定性以及三唑巴坦(TAZ)和舒巴坦(SBT)的抑酶效应。方法:用超声破碎法提取60株本院附属医院临床分离菌的β-内酰胺酶,用三维试验法检测β-内酰胺酶酶型;用紫外分光光度计检测酶活性及酶对CTX的水解率。结果:60株细菌中产超广谱酶者31株,产广谱酶者29株;两类酶的活性为非正态分布,其中位数分别为3 094 U和528 U(P<0.05)。3种常见菌的酶活性高低依次为大肠埃希菌、阴沟肠杆菌和铜绿假单孢菌(中位数分别为2656 U,1185 U和165.5 U,P<0.05)。超广谱酶对CTX的水解率(中位数20.10%)显著高于广谱酶(中位数3.15%)(P<0.05)。TAZ和SBT均能显著抑制两类酶对CTX的水解作用,但两种酶抑制剂的作用无差异(P>0.05)。结论:超广谱酶(ESBLs)对CTX的水解作用较广谱酶强,TAZ和SBT能有效抑制两类酶对CTX的水解,但其抑制作用强度基本相同。
Abstract:
Objective :To observe the stability of cefotaxime(CTX) to broad-and extended-spectrum β-lactamase,and to compare inhibiting-βlactamase activities of tazobactam and sulbactam. Methods : 60 strains of Gram-negative bacilli from Affiliated Hospital of North Sichuan Medical College were dealed with ultrasonic wave and their β-lactamases were extracted and these enzymes were detected by three-dimensional test.β-lactamase activitiy and hydrolysis of CTX were quantitated spectrophotometrically and calculated. Results :In these β-lactamases of 60 strains of Gram-negitive bacilli,the number of extended-spectrum β-lactamases and broad-spectrum β-lactamases were 31 and 29,respectively,and their medians of enzyme activities were 3 094 U and 528 U(P<0.05).The medians of β-lactamases activities of Escherichia coli,Enterobacter cloacae and Pseudomonas aeruginosa were 2 656 U,1 185 U and 165.5 U,respectively.The median of hydrolysis rates(HR) of CTX by ESBLs and BSBLs were 20.10% and 3.15%,respectively(P<0.05).The combination of CTX/TAZ and CTX/SBT(the ratio=2-1) could make the HR drop significantly(P<0.05),but the effects of TAZ and SBT were of no differences(P>0.05). Conclusion :The hydrolysis activities of ESBLs on CTX was higher than that of BSBLs.TAZ and SBT could effectively inhibit hydrolysis of CTX by β-lactamases,but these two inhibitors had little difference in their potency.
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