五倍子对产超广谱β-内酰胺酶的大肠埃希菌的体外抗菌和质粒消除作用

摘要

OBJECTIVE To screen Escherichia coli clinical isolates producing extended spectrum beta lactamase (ESBL) and to investigate antibacterial activity in vitro and plasmid elimination function of Galla Chinensis .METHODS Water decoc-ting was used to prepare Galla Chinensis water extract.Broth dilution was used for phenotype screening and confirmation of ESBL production.Gene of positive enzyme producing strain was detected by PCR.Agar serial dilution method was used to de-termine MIC.Replica plating was used to test plasmid elimination function.RESULTS Water extracts of Galla Chinensis showed antibacterial activity at 25 mg/mL.12 strains producing ESBL were screened from 50 Escherichia coli clinical isolates and the positive rate was 24%.Galla Chinensis eliminated plasmid of Escherichia coli producing ESBL(24 h elimination rate was 3.6%,the 48 h elimination rate was 4.8%).The plasmid eliminated strains showed MIC value decreased against the com-monly used antibiotics.CONCLUSION The results indicated potential antimicrobial activity of Galla Chinensis against clinical drug resistant strains.%目的：筛选产超广谱β-内酰胺酶的大肠埃希菌临床分离菌株，考察五倍子水提液的体外抗菌活性和质粒消除作用。方法采用水煎煮法制备五倍子水提液，肉汤稀释法进行产超广谱β-内酰胺酶菌株的表型初筛和确证，PCR 法对阳性产酶菌株进行基因检测，琼脂平板稀释法测定体外 MIC，影印培养法考察质粒消除作用。结果五倍子水提液对大肠埃希菌临床分离株具有明显的抗菌活性，MIC 值为25 mg／mL 左右，从50株大肠埃希菌临床分离菌株中筛选到产超广谱β-内酰胺酶菌株12株，阳性率为24％，五倍子对产超广谱β-内酰胺酶的大肠埃希菌的质粒有消除作用（24 h 消除率为3．6％，48 h 消除率为4．8％），质粒消除后菌株对氨苄西林等抗生素的 MIC 值降低。结论五倍子对临床耐药菌株具抗菌潜力。