【摘要】 本文对阴沟肠杆菌 Amp C酶进行了以下 5个方面研究 ,其内容和结果分别为 :(1)联合药敏实验 :用平皿二倍稀释法研究第四代头孢菌素头孢吡肟 ,第三代头孢菌素头孢他啶、头孢噻肟、头孢呋辛与 β-内酰胺酶抑制剂舒巴坦联合对 34株头孢他啶耐药菌 ,6株头孢他啶中敏菌及 15株头孢他啶敏感菌的体外抗菌活性。结果表明舒巴坦使头孢他啶对 32 .7% (18/ 5 5 )的阴沟肠杆菌的抗菌作用有明显抗菌增效作用。 96 .4%(5 3/ 5 5 )的阴沟肠杆菌对第四代头孢菌素头孢吡肟敏感。 (2 )酶稳定性实验 :紫外测定法测定 4株标准菌和 6株临床分离菌产生的 Amp C酶对 β-内酰胺类抗生素的水解率 ,结果表明阴沟肠杆菌产生的 β-内酰胺酶对第一代头孢菌素头孢唑林、头孢氨苄 ,第二代头孢菌素头孢克洛 ,第三代头孢菌素头孢哌酮及青霉素、氨苄西林、哌拉西林的水解率高。对第二代头孢菌素头孢呋辛、第三代头孢菌素头孢噻肟、头孢曲松、头孢他啶 ,第四代头孢菌素头孢吡肟以及亚胺培南、美洛培南和单环类 β-内酰胺抗生素氨曲南的水解率较低。 β-内酰胺酶抑制剂舒巴坦对 4株标准产酶菌及 6株临床分离菌产生的 β-内酰胺酶均无抑制作用 ,而三唑巴坦则对上述酶有明显的抑制作用。 (3) Amp C酶分子量测定 :用 SDS- PAGE测定酶的分子量 ,结更多还原

【Abstract】 The in vitro activities of fourth generation cephalosporins cefepime and β lactamase inhibitor sulbactam combined with cefuroxime, cefotaxime and ceftazidime against 34 strains ceftazidime resistant, 6 strains ceftazidime intermediate, and 15 strains ceftazidime susceptible Enterobacter cloacae selected from clinics; the stability of β lactam antibiotics to Amp C enzyme; the molecular weigh and isoelectric point of Amp C enzyme, and PCR amplification of amp C structure gene were studied. Results showed sulbactam could enhance the activity of ceftazidime against Enterobacter cloacae . The MICs of 32.7% Enterobacter cloacae decreased 4 folds and were in the range of intermediate and susceptibility. 96.4%(53/55) Enterobacter cloacae was susceptible to cefepime. The study of stability to β lactamase indicated that cephalexin, cefazolin, cefaclor, cefoperazone, penicillin, ampicillin and piperacillin were not stable to Amp C enzyme. However, the hydrolysis rates of cefotaxime, ceftriaxone, ceftazidime, tazobactam, imipenem, meropenem and cefepime were low. The hrdrolysis rate of sulbactam by enzymes extracted from 10 strains Enterobacter cloacae was almost 100%. The measurement of molecular weigh showed the molecular weigh of β lactamase extracted from 4 standard strains and 6 clinical isolates were 39.6kD. The measurement of isoelectric point of 10 strains Enterobacter cloacae showed the PI value of 2 standard strains were 8.35 and the PI value of 4 clinical isolates were in the range of 8.35~ 9.30 . Results of PCR amplification revealed that of 55 Enterobacter cloacae strains, 51 strains had amp C structure gene.更多还原