产超广谱β-内酰胺酶大肠埃希菌相关耐药基因研究

Resistant Genes Associated with Extended-spectrum β-Lactamases in Escherichia coli

目的了解常州地区大肠埃希菌耐药状况及β-内酰胺类耐药基因。方法用琼脂稀释法检测氨苄西林、哌拉西林、哌拉西林/他唑巴坦、头孢噻肟、头孢他啶、头孢吡肟、氨曲南和亚胺培南对大肠埃希菌的最低抑菌浓度,用聚合酶链反应(PCR)检测产超广谱β-内酰胺酶(ESBLs)大肠埃希菌TEM、SHV等17种耐药基因,并用DNA测序仪测序。结果80株大肠埃希菌ESBLs检出率为46.3%,37株大肠埃希菌检出TEM、SHV、CTX-M-1群、OXA-1群和DHA5种β-内酰胺酶基因,阳性率分别为81.1%、78.4%、21.6%、10.8%、5.4%;37株菌中有36株至少检出1种β-内酰胺酶基因,24株同时检出>2种β-内酰胺酶基因,1株菌最多同时检出4种β-内酰胺酶基因,只有1株未检出β-内酰胺酶基因。结论大肠埃希菌已携带多种β-内酰胺酶耐药基因,成为对β-内酰胺类抗菌药物耐药的重要原因之一。

OBJECTIVE To investigate resistance to antimicrobials and resistant genes associated with β-lactamases in Escherichia coli isolated from Changzhou district. METHODS Minimum inhibitory concentrations （MIC） of ampicillin,piperacillin, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, aztreonam and imipenem were determined by agar dilution. Seventeen resistant genes of E. coli encoding β-lactamases including TEM and SHV were detected by PCR amplification and sequenced by DNA sequencer. RESULTS The detecting rates of extendedspectrum β-lactamases in 80 Klebsiella pneumoniae isolates was 46.3 % （37/80）. Five β-lactamase resistant genes including TEM,SHV,CTX-M-lgroup,OXA-lgroup and DHA in 37 isolates were found, and their rates were 81. 1% ,78.4% ,21.6% , 10.8% and 5.4%, respectively. Of 37 strains, at least one β-lactamase gene was detected in 36 strains. More than two β-lactamase resistant genes were simultaneously isolated from 24 strains. Furthermore, four β-1actamase resistant genes were found in one strain. Only one strain wasn＇t detected out β-lactamase gene. CONCLUSIONS E. coli has carried various kinds of β-lactamase resistant genes in Changzhou district, which become the important causes of resistance to β-lactam antimicrobials.