临床产ESBLs细菌的耐药特征和基因分型的研究

Identification, Antibacterial Susceptibility and Gene Typing of Clinical ESBLs-producing Bacteria

目的了解产超广谱β-内酰胺酶(ESBLs)细菌的流行和耐药特点,初步对产ESBLs细菌进行基因分型,确立耐药基因的位点和种类.方法收集分离鉴定菌株,通过K-B法药敏实验初筛以确认产ESBLs菌株,并对ESBLs基因进行初步分型.结果分离到产ESBLs细菌88株,检出率为38.9%,其中肺炎克雷伯菌阳性率为43.1%、大肠埃希菌阳性率为33.3%;产ESBLs细菌对青霉素类、氨曲南及头孢菌素类耐药率约为90%～100%,加用酶抑制剂克拉维酸或他唑巴坦后耐药率降为18.7%～46.8%;PCR初步分型结果表明:大多数产ESBLs细菌携带TEM型和SHV型β-内酰胺酶基因,其中单独携带TEM型基因的占42%,单独携带SHV型基因的占12.5%,携带两种基因的占31.8%.结论产ESBLs细菌具有多重耐药的特点;产ESBLs的大肠埃希菌和肺炎克雷伯菌大都携带TEM和(或)SHV型β-内酰胺酶基因,其中绝大部分产TEM型β-内酰胺酶.

OBJECTIVE To study the prevalence of extended spectrum β-lactamases (ESBLs) and the resistance of ESBLs-producing bacteria. The polymerase chain reaction (PCR) was used to establish an effective method for the initial typing of ESBLs. METHODS ESBLs-producing strains among clinical isolates of Escherichia coli and Klebsiella pneumoniae were detected by K-B method. The DNA of bacteria was extracted by TriPure Isolation Reagent and typed initially by polymerase chain reaction. RESULTS The positive rate of ESBLs-producing isolates in E. coli and K. pneumoniae was 33.3% and 43.1%, respectively. The resistant rates of ESBLs-producing isolates against penicillins, aztreonam and the third generation cephalosporins were about 90-100%. When combined with the β-lactamase inhibitors, tazobactam and clavulanic acid,the resistant rates were about 16.7-46.8%. The result of PCR showed that the rates of TEM type, SHV type and TEM with SHV type in Enterobacteriaceae were 42.0%, 31.8% and 12.5%, respectively. CONCLUSIONS The ESBLs-producing isolates are multi-resistant. Most of the ESBLs-producing E. coli and K. pneumoniae carry TEM related genes or /and SHV related genes. Most carry TEM related genes.