Kinetically Controlled Cynthesis of Cefaclor using Penicillin G Acylase

Enzymatic synthesis of cefaclor from 7-aminodesacetoxymethyl-3-chlorocephalosporainc acid(6-ACCA) and phenylglycine derivatives using penicillin G acylase was studied .Many factors that affect the conversion of 7-ACCA to cefaclor were examined.The immobilized enzyme from Bacillis megaterium gave a better catalytic properties and the higher conversion was obtained using phenylglycine methyl ester(PGME) as acyl donor.And the external mass transfer limitation could be eliminated when the stirring rate was more than 150r/min.Low temperature was beneficial for the synthesis and the results showed that the synthetase activity was hardly influenced by temperature while the amidase activity was affected greatly by temperature.The optimum reaction conditions were determined at pH 6.5 and 10℃,respectively.The best 7-ACCA conversion of 56% was achieved when the intial concentration of 7-ACCA and PGME was at 50 mM and 150mM,respectively.

2015年至2017年上海地区无乳链球菌临床感染情况及耐药性分析

目的 :了解妇产科医院2015年至2017年的无乳链球菌感染和耐药情况。方法 :回顾分析上海市第一妇婴保健院2015年至2017年产科、妇科及男性科患者的无乳链球菌阳性率;选取2017年共374例无乳链球菌阳性病例进行药敏试验,并对红霉素耐药、克林霉素敏感的菌株进行D试验检测。结果:2015年我院产科、妇科及男性科患者无乳链球菌阳性率分别为2.69%(88/3 267)、3.10%(101/3 255)、5.93%(28/472),2016年分别为3.94%(378/9 578)、3.42%(92/2 685)、7.49%(14/187),2017年分别为3.90%(251/6 429)、4.10%(110/2 682)、7.22%(13/180);2015年至2017年产科孕妇的无乳链球菌阳性率为3.72%(717/19 274)。2017年,无乳链球菌对红霉素、克林霉素、左氧氟沙星的耐药率分别为63.37%(237/374)、53.48%(200/374)和25.13%(94/374),未发现对青霉素、头孢曲松、利奈唑胺、万古霉素耐药的菌株。结论:2015年至2017年,无乳链球菌感染有逐年严重的趋势,应受到重视;对孕妇进行无乳链球菌筛查有重要意义;需注重对非孕妇成人患者的无乳链球菌筛查;青霉素类抗生素仍是治疗无乳链球菌感染的首选药物。