摘要
目的 研究AmpC酶和超广谱 β 内酰胺酶 (ESBL)在阴沟肠杆菌中的流行情况及对其耐药性的影响。方法 琼脂稀释法测定最低抑菌浓度 (MIC) ,三维试验、等电聚焦电泳、接合试验及聚合酶链反应分析耐药菌的产酶情况。结果 10 6株阴沟肠杆菌中 ,单纯高产AmpC酶者、单纯产ESBL者、高产AmpC酶并产ESBL者分别占 16 0 %、10 4 %、13 2 %。CTX M型和SHV型ESBL的检出率分别为 17 0 % (18/ 10 6 )和 6 6 % (7/ 10 6 )。碳青霉烯类抗生素对阴沟肠杆菌均有很好的抗菌活性(MIC90≤ 2 μg/ml)。单纯高产AmpC酶菌对头孢吡肟、阿米卡星、庆大霉素和环丙沙星的敏感率均超过 70 % ;单纯产ESBL菌对哌拉西林 /他唑巴坦、头孢哌酮 /舒巴坦、环丙沙星和阿米卡星的敏感率均超过 6 0 % ;高产AmpC酶并产ESBL菌对除碳青霉烯类外的其他抗生素的敏感率均低于 2 5 %。结论 CTX M型ESBL已经在阴沟肠杆菌中流行。产ESBL和高产AmpC酶同样是导致阴沟肠杆菌对第 3代头孢菌素耐药的重要原因。ESBL在高产AmpC酶菌株中的流行增强了此类菌株的耐药性。
Objective To investigate the expression of AmpC β-lactamases and ESBL among clinical isolates of E cloacae and its impact on antibiotic susceptibility Methods Antibiotic susceptibility was determined by standard agar dilution procedures β-lactamases of the isolates with decreased susceptibilities to ceftazidime,cefotaxime,ceftriaxon or aztreonam were investigated by three-dimensional extract tests , isoelectric focusing overlay technique, conjugation experiments and PCR Results Among 106 E cloacae isolates,16 0% produced only high-level AmpC β-lactamases,10 4% produced only ESBL, 13 2% produced both high-level AmpC β-lactamases and ESBL 18 isolates(17 0%)carried CTX-M-type ESBL and 7 isolates (6 6%) carried SHV-type ESBL All carbapenems showed high activity against E cloacae strains (MIC90≤2 μg/ml) More than 70% of the isolates producing only high-level AmpC β-lactamases were susceptible to cefepime, amikacin, gentamicin or ciprofloxacin More than 60% of the isolates producing only ESBL were susceptible to piperacillin/tazobactam, cefoperazone/sulbactam, ciprofloxacin or amikacin The susceptible rates of the isolates producing both high-level AmpC β-lactamases and ESBL to tested antimicrobial agents other than carbapenems were all lower than 25% Conclusion CTX-M-type ESBL was prevalent among clinical isolates of E cloacae Resistance to expanded-spectrum cephalosporins in E cloacae was mediated not only by AmpC β-lactamases but also by ESBL Expression of ESBL in high-level AmpC β-lactamases producing strains resulted in a significant rise in resistance level
出处
《中华医学杂志》
CAS
CSCD
北大核心
2002年第19期1355-1358,共4页
National Medical Journal of China
