上海地区产超广谱β内酰胺酶大肠埃希菌和肺炎克雷伯菌的实验和临床研究

The laboratory and clinical stady of extended-spectrum β-lactamases in Escherichia coli and Klebsiella pneumoniael in Shanghai hospitals

目的 :了解上海地区临床分离大肠埃希菌及肺炎克雷伯菌中超广谱 β内酰胺酶 (ESBLs)的发生率、流行情况、对抗菌药物的耐药性、产酶基因的转移特征以及感染类型和医院感染的临床特征。方法 :用双纸片法和表型确证试验 (MIC法 )检测ESBLs产生株 ;Kirby Bauer(KB)法测定细菌对抗菌药物的敏感性 ;接合转移试验检测产酶基因的可传播性 ;对上述细菌感染中部分患者进行病史调查与分析。结果 :肺炎克雷伯菌和大肠埃希菌中ESBLs产生株的发生率分别为 3 9.4 %、2 1.5 % ,ES BLs产生株对于大多数 β内酰胺类药物明显耐药 ,并对氨基糖苷类、氟喹诺酮类多数耐药 ,对亚胺培南则呈现敏感 ;ESBLs产生株可以通过接合转移将其产酶基因转移给敏感株 ,转移频率多在 10 -3～ 10 -7,双纸片法和表型确证试验结果显示转移接合子具有与产ESBLs供体菌相同的耐药表型 ,质粒提取、聚合酶链反应 (PCR)检测结果两者亦相同 ;ESBLs产生株主要引起医院感染且患者的转归较差。结论 :肺炎克雷伯菌和大肠埃希菌ESBLs产生株大多为多重耐药菌 ;ESBLs产生株可通过结合转移将产酶基因转移给敏感菌 ,导致耐药性传播 ;ESBLs产生株为引起医院感染的重要病原菌 ,治疗较困难 ,需要加强检测。

To investigate the prevalence, resistance and transfer of gene encoding ESBLs in ESBL producing strains in Shanghai hospitals. Medical history of patients infected with ESBLs producing strains were reviewed. Methods:ESBL producing strains were detected by double disc test and confirmed by agar dilution test. Suscepibility testing were done by Kirby Bauer method. Gene encoding ESBLs were transferred by conjugation. History of patients infected by these organisms were reviewed. Results:The incidence of ESBL producing strains was 39.4% in K. pneumoniae and 21.5% in E. coli . ESBL producing strains were more resistant to most β lactams and were more resistant than ESBL negative strains, however all strains were susceptible to imipenem. Most ESBL producing strains were also resistant to fluoroquinolones and aminoglycosides. ESBL encoding gene can be transferred by conjugation at the rate of 10 -4 , Results of plasmid extraction and PCR were the same between transconjugants and donor strains. ESBL producing strains mainly cause nosocomial infections, and the outcome of these patients were usually poor. Conclusions:The incidence of ESBL producing strains in K.pneumoniae and E.coli is rather high, these strains are usually resistant to most β lactam antibiotics. The gene encoding ESBLs strains can be tranferred by conjugation. ESBL producing strains mainly cause nosocomial infections with poorer outcome. It is important to detect the ESBL producing strains in clinical microbiology laboratory.