健康学生大肠埃希菌第1类整合子的鉴定及特征

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

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 bp10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。

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 aadAl-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 sulfamethoxazoletrimethoprim. Conclusion The different kinds of class 1 integrons exist in E. coli from the healthy students, and determine the multiple- resistant antibiotics.