健康学生大肠埃希菌第1类整合子的鉴定及特征

目的：探讨健康学生肠道大肠埃希菌携带第1类整合子的分布及所含基因盒的特征。方法：常规方法分离大肠埃希菌；纸片扩散法对10种抗生素进行耐药性监测和分析；PCR鉴定第1类整合子阳性株；PCR产物测序并对结果进行分析。结果：从97份标本中鉴定出大肠埃希菌76株，其中25株（32.8%）为多重耐药，耐药谱为复合磺胺-氨苄西林-四环素-红霉素-链霉素。25株中有14株(56.0%)鉴定出1类整合子，1 800 bp 10株, 750 bp 4株。PCR产物测序得知1 800 bp整合子携带aadA1-dfrA14-orf基因盒，传递对氨基糖苷类-磺胺类抗菌药物的耐药性；750 bp整合子携带dfrA14基因盒，传递对磺胺类抗菌药物的耐药性。结论: 不同种类的1类整合子存在于健康人大肠埃希菌中，携带耐药基因盒，决定多重耐药性。 

Identification and characterization of class 1 integron among E. coli from healthy students' enteric strains

Objective To explore the distribution and characterization of class 1 integrons in E.coli from healthy feces,and to elucidate the status of gene-cassettes.Methods Routine method was used to isolate E.coli,antibiotics susceptibility was tested by the disk diffusion method;class 1 integron was detected by PCR assay;PCR products were sequenced and analyzed.Results Of 97 samples,76 isolates were identified,and 25 isolates were multiple-drug resistant.The antibiogram was sulfamethoxazole-trimethoprim,ampicillin,streptomycin,tetracycline,erythromycin.14 of 25 isolates carried class 1 integrons,and the size of integrons differed from 1 800 bp(10 strains) to 750 bp(4 strains).The sequenced PCR product demonstrated that the 1 800 bp integron laboured aadA1-dfrA14-orf gene cassette conferred the resistance to sulfamethoxazole-timethoprim,streptomycin and aminoglycoside;the 750 bp integron laboured dfrA14 gene cassette conferred the resistance to sulfamethoxazole-trimethoprim.Conclusion The different kinds of class 1 integrons exist in E.coli from the healthy students,and determine the multiple-resistant antibiotics.