Studies on hydrolysis of cefotaxime by broad and extended-spectrum-β-lactamase and inhibitory actions of tazobactam and sulbactam

Key words: 
• cefotaxime /
• tazobactam /
• sulbactam /
• extended-spectrum β-lactamase /
• broad-spectrum β-lactamase /
• Gram-negative bacilli /
• hydrolysis

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.